Madden had weapons before and it obviously didnt do much. The real issue is the fact that ratings dont have enough animations to properly represent what they really are. Saying weapons adds more to the game is really just saying "I like my player to have a label on him that tells me what he is good at".
The way to add real tangible life to a player is to give personalities to them like in Head Coach 09 for example. Some guys would get upset about not enough playing time while others were ok with sharing time, some would demand ridiculous contracts while others would take pay cuts because they were team players, some would lose moral and get upset about losing/not having enough talent on the team. That adds something to the game besides "Look my CB is a Press King(or whatever 2k8 called it)" Weapons are a simplistic way to rate players and IMO is extremely lazy and would lead to players being too much alike in madden.
As the the OP, I am not exactly sure why you would need two different ratings for acceleration. If you mean explosiveness would be their ability to make big plays, then there isnt a need for it. If you want to take a WR with poor WR abilities and let him make plays, run screens, underneath routes, and wild cat to let him get the ball and run after the catch. His running ability(juke spin ect ect) will allow him to make big plays out of nothing.
If you think that CJ is to slow compared to other players, I have amazing news for you. There is a slider for that. It is call speed threshold. Simply move it down to 0 and watch CJ just glide by the defense. If you are an online only player then there isnt really anything you can do. I know it sucks but the game was tried to be made as balanced as it could.