Not much, other than not having an Auction House. All others do. But that is not something I would want to see in a UFC Ultimate Team. From my understanding you keep all fighters you obtain through packs (I first thought they would expire but that does not seem to be the case, just Tony F.)
If this game gets a Auction House then eventually everyone is going to have every champ out there. It's not something I would like to see. I don't even like the champions being there in the first place.
I'd rather have seen you could get one of these fighter cards as your coach/trainer or whatever, so you could get the stat boost from the card, but not actually have to fight a UFC fighter every other match. This makes it just like Quick Match, except that you have to pay to improve your fighter. (Be it money or time).
The mode is filled with microtransactions to improve the fighters. While I think the earnings for winning matches are fair, and the daily objectives are rewarding, you still have to grind out all of these.
I think they should reward being active. Give people a bonus for logging in to the game. Many mobile games do too. If you want to have microtransactions in the game, the best approach is to also be generous with the content you are selling. I think for EA especially, it is in their best interest to do it.
They could give daily login bonuses just so people keep coming back. This gives a sense of progress and it won't take them much time at all. And it also makes it so that people will stick around for the mode. They could give anything from coins/packs/ and perhaps close it off with a free random fighter for anyone that checked in a certain amount of times, and then reset the thing at the end of the month.
Madden UT is a pretty generous mode in that every weekend it has special content based on matches that are happening. I dont know if UFC 2 UT did anything like that. I do know they had new cards based on what happened. But that essentially required you to put money or coins into the game again, just to obtain them.
They could make events based on MMA events that are happening. For example, beat use Holm to beat Cyborg. Win a free pack if you do. Or whatever.
I can see why they did that with the perks though. I think for balance, that is a good approach. Now people wont be full on perks anytime you face them again. They'll think twice before using it.