And that's why your point is utterly flawed. There is no connection between ads and good games. In fact, the sole thing that is guaranteed, is that the game is gonna feel weird/worse because it has ads. Just hoping ads might somehow enable someone to make a better game is really naive.
Deus Ex 3 is a really bad example anyway, because it sold like crazy. Considering their huge financial success it's all the more disappointing, that they are pulling this stunt. You'd expect something like this from a desperate developer, who doesn't see any other way to break even. So this is really just another greedy cash grab that hardly deserves any sympathy.
All of this isn't even covering that the game is from _Canada_ of all places, where the government pays at least half the salaries of all programmers such a developer employs (the government is trying to make their country number 1 in the gaming industry). That means their costs were really low in the first place.