Sure, and so is an opinion on what makes a good movie. When there is general consensus, however, on what a "good" movie is and a "bad" movie, then the subjectivity sort of becomes moot. No one would call Liberal Arts a "rigorous" field nor would anyone call Engineering an "easy" discipline.
It still remains too subjective to gauge any meaningful point. Depending on one's point of view that person will always side with their bias either through ignorance, to preserve their own job security, prejudice towards or misunderstanding of the 'other side' (sometimes all four).
As to your point about movies; ever heard of a movie so historically bad it's considered good by general consensus? Subjectivity is alive and well and ever fluid. It will always be a part of any conversation concerning society.
Society decides this collectively. When an Engineer can find a good job for a good wage, and achieves good job satisfaction, then this is considered a "good" job with a "high" socio-economic standing. When a Liberal Arts grad can't find any job and ends up working at McDonalds, society has clearly decided that their "field" is not sufficiently valuable to allow them to obtain gainful employment.
Objection.
1. And when an Engineer cannot immediately find a job specific to their expertise, i.e. they must go the McDonalds route? Or because of either socio-economic recession or job market saturation? Hath society deemed them unworthy? Or is it perhaps the result of a badly managed economy.
Society's decision = minus 1
2. Nowadays pretty much everybody that isn't a footballer or hasn't been born into wealth, celebrity status or have influential or otherwise company/asset owning parents (from which to provide a future job for their offspring) is expected to stomach working menial "McJobs" no matter the level of their education, intellect and qualifications. Judging by this factor it seems society clearly wants none of us around unless we are of specific origins.
Society's decision = minus 2
3. A successful filmmaker with an Arts degree is also considered a person with a "good" job with a "high" socio-economic standing. So really it's all just about how successful an individual becomes irrespective of their area of expertise or of society's apparent decision to cull them from the pack.
Society's decision = minus 3
I do agree that collectively society does play a part in influencing the "status" of certain fields of interest/occupations (how could it not) but upon closer inspection and comparison with what life shows us it's not a convincing enough argument to say that society and society alone knows exactly what is and is not useful in terms of humanity's progress. Sometimes it takes individuals to show society what is useful, what might be useful in future and what was useful before that can be useful again.
This is really just a lack of education or knowledge, not a valid "opinion" on the usefulness of bees. Sort of how farmers routinely eradicated wolf populations only to find they were keystone predators and their deaths disrupted ecosystems substantially. There is no particular "value" to say, a Liberal Arts education if does not result in a meaningful job that clearly serves a useful purpose in society.
So true of any field of education then, not only the Arts.
There is however always an innate "value" to education, at least that's what i believe. The "value" of the education is to the individual - they will be the ones using it to better themselves, their children and thus society. The "useful purpose" to society is when/if it allows that individual to grow and flourish rather than simply attempt to survive. This is one of the major problems of why we've witnessed such a decline of great thinkers, creators and genuine intellectuals - everyone is encouraged to be too busy surviving rather than being concerned about developing as a person and progressing as a species towards something better. That's why, as you said, the 1950s were such a different time to ours and we've seen a decline in terms of certain human potential since then.
Does the time invested in a Liberal Arts education, for example, enable an individual to contribute to society in unique and meaningful ways that they could not do without this education? You don't see "self-taught" Enigneers building bridges for example, so this is clearly something that one needs to apply onself with rigorous study.
Well yes, it does. As I said before education is never a wasted resource.
I don't disagree with the point you're trying to make - i.e. it's not possible to be a "self-taught" engineer (except for the first human to ever build something

). I just don't see the relevance. Are you saying too many people are getting educations in fields other than Engineering and the Sciences?
In which case that's a symptom of a field people flock to when they are sufficiently interested in it but also when there are sufficient accessible opportunities to fund an education and make a living out of it. For example, you can have someone who loves science and astrology, loved it since their school days but where are the opportunities to secure sufficient funding to go to a quality University or to find gainful employment as a scientist? They're certainly not advertised in schools or colleges by experts in the field. No visiting employment councillors for budding young scientists. That's not the fault of the Arts community (they also don't exactly whip out the Steven Spielbergs or Chris Nolan's to come visit), it's entirely the fault of the Scientific community's lack of initiative.
And that is why I leave the possibility open for truly gifted individuals in the arts to contribute in a unique and meaningful way.
You're so gracious, thank you sir!

(Apologies but I simply had to make fun of the brazenly "superior" tone).
Many students who puruse education in "vague" or "non-rigorous" disciplines are not particularly talented at what they have chosen to study, it was simply something that they did not find particularly demanding and allowed them to avoid the reality of finding an actual job for 4-6 years as they went to college.
That is a very silly and derogatory assumption to try and pass off as some kind of imaginary fact.
Forgive the assumption but here you assume the manner of someone who knows no practical experience of working in the creative industry and yet deems it worthy to confidently assume there's no expertise that goes in or comes out. That it's some kind of stereotypical easy street for less individuals because that's what you heard one day but never endeavoured to dig deeper. And particularly the comment about "an actual job" makes your words sound like a textbook caricature stereotype of the types we can all imagine yelling, "get a real job ya bums!". Because it's not a "real job" (whatever that means) unless it's approved by you/somebody/anybody, correct.
I'm sorry but there was no amount of intelligence put into this part of your post.
I would agree with this, but I think there is often an insufficient distinction between an Engineer and a Liberal Arts student where the degree of achievement is simply not comparable and in many cases the standard are so low that there is little to no achievement at all in some cases. I have even seen this in many disciplines in science that lack proper structure or rigor in comparison to their larger field of study and they are not particularly well-regarded in scientific communities. You can imagine where some of the poorly-structured social disciplines must rank in comparison.
From my point of view; we should not become a society completely controlled and led by a notion of "superior endeavours" and "inferior endeavours" - as if "these endeavours" are fit for the master race among us and "these other endeavours"... well they're for the less developed plebs filling our streets. Excellence in any field should be encouraged. If we want to encourage more excellence/interest in a particular area then as a society we need to demand better standards of general public education and the equal representation of subjects/fields of endeavour.
I think the issue here is that "excellence" in a field (whatever that field might be) has taken a back seat to pursuing whatever you "enjoy" without any sense of whether you are actually any good at what you have chosen to "study".
That is an interesting observation. I would ask; Can you truly "excel" in a field you do not truly enjoy?