Well, it might be because of the controls and the graphics, which the Wii lacks in at least one of these departments. I believe that in the world of HD that is today, if you're playing a sports game, you have to see sweat on the players, you have to see the grass getting more and more ''dirty,'' etc.
And about the controls, I can't picture a kick by a wrist motion. It just doesn't make sense, and people might be looking for that. Sure, a button press is not better, but at least it feels as if you're watching a real game on TV, not watching one in front of hyperactive kids that can't control their arms once they leave the comfort of a couch or something. That's my opinion though, some people might prefer this control option over the HD versions.
Also, isn't there an instant roster change in the new EA games that monitors every trades going on in various leagues and all? I'm not sure if the Wii has that, but it might be another selling point for the HD versions.
I hope that makes sense...! @_@
Random game thought :
Why is Bionic Commando Rearmed 2 getting so much hate? We finally get a real game and they're not even satisfied... I'm starting to hate the gaming community so f****** much...