I've heard the "mile wide, inch deep" line thrown around plenty of times in the past. I've always assumed FD's development plan would be to build out sufficient breadth so that they can really do depth well. Unfortunately, I don't really see how Engineers really helped with that. Maybe it isn't their plan at all. I don't know.
At the risk of repeating myself - I think ongoing game development is both a blessing and a curse, especially when the scope of the game is large. The game can't be developed for 10 years and then released, so it has to be done piecemeal. That means that features come in an order that has to be right for development, but not necessarily right for the players. It means mistakes and bugs are there for all to see. Ideas that don't work behind closed doors can be scrapped and started again with players being none the wiser. In ongoing development you have to commit and hope you've made the right decision. Or scrap them and start again - which is just not going to happen.
It also means that each release has to have some headline feature that sells enough copies to continue the development - in the case of Engineers it was understandably a headline feature and as such it gained a lot of attention. But in the context of the finished game (or the game in another 6-12 months) I'm not sure that it will be that significant. I see it as something else to do in a game that has/will have a myriad of other things to do. Players however understandably focus on the next feature and that's understandable. It's seen as 'the next thing to do', rather than something else to do.
Personally I've avoided the mental choice of going for 'X Upgrade' and instead just played the game and had fun collecting stuff on planets etc. I've done missions and got rep with factions, had fun doing a variety of stuff and enjoying the many small quality of life features in the 2.1 release. I don't really need any of the stuff the engineers offer - but at some point Ill drop by and see what I can get.
That said there's clearly stuff that needs sorting out and many people have made some excellent suggestions.