What would you take away from the current game to have accurate sidelines? There's only so many resources to go around, doubling (and then some) the number of players to render isn't really all that much of an 'excuse' as it is a reason.
That being said, It's been mentioned already for next gen, we'll see what pans out.
Edit: via quick search -
"When we introduce our new sidelines and crowd on Xbox One and PlayStation 4, it’s not just going to be a static crowd and looping animation. They’re going to react to things happening, whether it’s exploding for a big play or deflating. It’s a huge focus for us, and something we’re going to blow out in Generation 4."
http://www.operationsports.com/forum...sion-more.html