No, I don't actually. (I kinda do from personal perspective, but for the game it's a terrible idea)
I think the fragmentation of occupation is Elite's best feature. Yet you still see people tunnel-visioning and grinding (and complaining about it, like someone forced them to do it)
Can you imagine the situation where they have to (in their minds) complete a week long mission to earn substantial money? What if it fails? Due to a bug or pilot error? Can you imagine the situation where earning money was ACUALLY HARD?
The forum is toxic through the roof already...
Seems to me exploration is the ideal candidate for time consuming but high paying missions. If the player goes exploring they may be committed to that task at the expense of all others until they return to dock.
Variety is fine, as is choice. One of those choices can be to take on one big, complex & time consuming mission instead of lots of little ones, or other activities. Unlocking an Engineer is a good example of a time consuming & reasonably complex task completed possibly over several sessions with a significant reward at the end. I see no reason to exclude those that want this just because others don't want it, it doesn't affect them if they don't take the mission.
The hilarity on the forum atm seems to be about the Cr/Hr rather than the actual credits. I earned my Trade Elite in Dec'15, in the latter stages I was focused & turning over around an average of 7.5mCr/Hr (peak was around 9, but it would take me around 4-5Hrs to complete a circuit).
I would suggest 10mCr/Hr is a decent target, anything over that should be challenging, anything less should be easy/dull. I'm sure plenty will disagree with my 10mCr/Hr figure, where would you draw the line?