Mankind having evolved past greed and now working only to better themselves.
No conflict on TNG among the crew because of all this enlightened evolving.
The no money part - if there's no money, there's no economy and no trade. You need an accepted medium of exchange or else you have to have a barter system.
TNG's crew had no real interpersonal conflict unless an outsider came in (Shelby) who was treated relatively poorly by the crew (Riker), who should've been professional enough to understand that she's there for a reason and to do a job.
Lack of visible enlisted crew with actual rank pips/stripes. Not everyone's an officer. Why spend 4 years at the academy to be a yeoman in TNG's timeframe? Someone has to fill clerical duties for the admirals at Starbases, and an ensign sure wouldn't do it.
Jumpsuits. Those never looked comfortable nor like uniforms
, unlike the Wrath of Khan uniforms.
Wrath of Khan uniform derivatives - the crewneck and no-shirt variants. Better to use transitional uniforms, like Excelsior and Ambassador were transitional ships to the Enterprise D. I've seen a few here and at the Uniform site.
Dress uniforms - they were actual dresses. Later uniforms with just gold piping were better, but I'm sure there's a happy medium to be had.
Admiral uniforms - they changed every time an admiral appeared with no explanation.
DS9/VOY jumpsuits - why?
No political exploration - just for an episode or a scene, discuss the political structure of the Federation. At best, it's a republic, with elected representatives sent to a Federation Council of some sort, leaving the individual planets to manage their own internal affairs without interference from other species. What's the President's term, and how is he elected/selected? Is it Federation-wide, or is he elected from the Federation Council, similar to how a Prime Minister works in some governments?
No advancement - I get it with contracts and all, but why would Riker stall his career for over 12 years to stay on the Enterprise, when he could've been an admiral by then? Similarly Picard, Crusher, La Forge, etc. The original crew had rank advancement much more quickly than the TNG crew.
Carpet/Upholstery civilian garb - I've seriously seen some of those civilian outfits on couches in the late 80s/early 90s.
Overuse of Miranda/Excelsior/Oberth ships - are there not any other classes of vessel in Starfleet? We should've seen New Orleans, Centaur, Constitution, et al, all over the place. A perfect opportunity for TNG-R to spruce things up, which they likely won't take.
No exploration of Pike or April's time on the Enterprise - aside from the Cage/Menagerie, and the animated episode with April, we don't hear anything about Captain Robert April's time on the Enterprise, and he remains really nothing more than conjecture.
No exploration of 1701B or 1701C - Perhaps after Generations or even during, we could get at least some notice that Harriman either retired or transferred, and what happened to Demora Sulu, at least in passing. And when did 1701-C launch? Little things yes, but they make a difference.
Archons in Enterprise - It would've been nice to see a real live Daedalus class vessel, perhaps even mention the USS Archon getting lost, or one of the other Daedalus class getting lost somewhere.
Orions in Next Generation, DS9, Voyager - nowhere to be found. All we saw was Rachel Nichols in ST09 as an example of a 'normal' Orion in Starfleet.
There's more if I could think of it, but that should do for now.