There's a long list of things I'd like to see.
A big one for me would be adding all the high and low A roster spots. To clarify I don't need the teams playable (I've seen people shoot this want down because of added statiums and game space for playable games.) I just want the roster spots. Keep only MLB, AAA and AA playable. But instead of only 15 men in reserve (92 total) give me full high and low A squads in reserves (130 total) I know that's a lot of players to have in reserves but just imagine what the people who do the full minors roster could do with that.
I also echo the downloadable draft class would be awesome.
3 team trades and or trade for cash. Although with trade logic I think the CPU would drastically mess this up.
This one is a minor nit pick. But ill ride this train forever. Ability to edit face scanned players hair and facial hair. Example in real life last year Joey Gallo gets traded to NYY yet in my franchise he did not. So SDS removes facial hair. So now in franchise he's just clean shaven on the Rangers. Likewise let's say Bryce Harper gets trades to NYY in fictional franchise. Now he's on NYY with a beard and nothing i can do about it. Again minor nitpic but I want it.
I know we can't do fights anymore (sadly) but some more or different frustration animations would be nice.
Finally the ability to have at least some input on customizing your schedule would be nice. Nothing to drastically I'd be happy even with being able to pick the interleauge teams you face.
There probably more but that's what I got for now