Maybe it's too complicated for them......
That's assuming it's still all f*&ked up as the videos now make it look.
Think about it, what do they need to do to get pressure right? It's not a simple solution to just make the fatigue model harsher because that would just make every AI player knackered after 60 min in every game.
So only a fatigue model isn't enough, you then have to look at play patterens and the total lack of them. They would need to build an AI that is smart enough to react dynamically to the match actions. Know when to pressure, when to back off, which parts of the pitch and even opposition players need to be pressured. So if they take a lead they can sit back and defend more, go behind they would have to attack more and leave more gaps, playing different styles would mean they would have to adjust in real time to continue to be able to offer a realistic/suitable match.
To not have constant pressure means they would have to program the AI to know when they can back off, when they need to attack, when they need to drop back and protect a lead. But they don't, even when putting the formations and custom tactics to extremes all it does is slightly adjust the play. I created all kinds of tactics for 10 and did it for my own team in the WC match but even if yuo set up a team to play like Inter v Barca with everything set to ultra defense they still all move the same way with a "counter attack" making their back line push up to the HW line! All it does is slight tweaks on the same play model.
So how can they make a "balanced" game without having to incorporate high level AI?.....just make the teams play very similar, have a simple "always pressure" AI model and you can slightly tweak it in custom tactics. Because all custom tactics does is effect individual players (less pressure, agression, etc) but doesn't really effect the actual teamplay.
So could it just be that they haven't got the AI to a level where they can do a proper match based on football and they have to go down this route?