Really, Xcom isn't "dumb" at all. The 1ap/1action is a very simple system that enables you to focus on what is important : moving around, placement, cover, actual actions... In short, tactics rather than endless mathematics. One could argue Xcom isn't even the same genre than DOS, but actually they are very close. Just replace shotguns with melee, assault rifles with bows, rocket launchers with fireballs, and you've got yourself a serious lookalike.
Or let's take a more extreme example, chess. Chess is essentially a tactical game with 1 action per turn for both players.
Involving more numbers and more maths isn't adding a layer of complexity or anything meaningful. simplifying the system isn't dumbing down. To think so is either elitist or precisely naive. I'll welcome a system where I don't have to involve numbers in the 50+ whenever I try to plan two or three turns ahead because it's just a useless annoyance as it is.
Again, the only thing that could make the whole plan fail is if they can't deliver a proper system that gives each type of weapon a specific ability or set of bonuses/maluses.
Other than that, they are developpers and developpers should always aim for the most simple form of gameplay that would still carry a lot of tactical / fun / challenging value. This is indeed their job and it absolutely doesn't mean they are dumbing down anything.
