I agree the opposite field power needs to be tweaked, but you are way too general on saying someone can't hit an oppo bomb just because they don't hit 30 HR's. These guys can hit opposite field home runs if they specifically try to hit oppo, so in 2K if you hold the stick that way, you should be able to do it.
Some guys have much better power when they get extended on an outside pitch and will hit it just as far to the opposite field. An example of this are guys like Juan Uribe and Pablo Sandoval on the Giants that just make a lot of late contact on fastballs that allow them to hit opposite field HR.
This is one of my biggest gripes with recent games that would add greatly to realism...
Guys that are dead pull hitters in real life should be made to play that way in this game though... meaning they receive a penalty in power.contact if the user tries to hit opposite field with them in the game.
The problem in the game isn't so much that it's super overpowered, but that the hitting mechanics don't really penalize guys for being pull-hitters or jammed enough so you can just sit back and let every ball get deep... which = opposite field BOMBS you don't normally see.