I can see why you say that, but honestly, combos aren't as cheesy as keeping someone in full guard (at least from a competitive standpoint). At least it's making a conscious attempt to keep it competitive rather than kicking the lead leg a thousand times knowing I'll get a for-sure victory. If I'm throwing a combo, I'm increasing my risk to being hit as opposed to being in full guard where there's little to no risk involved.
I prefer playing a more tactical game, but in competitive gameplay, it forces me to play likewise. It's why I can't wait for UFC 3.