Ascension suffers from a common problem with deck-builders, and one which Donald X has stated multiple times he purposely avoided. Namely, the mechanic is based around a pool of available cards, which are replaced with new cards from the top of a face-down deck when they are bought. I have rarely known this not to lead to major suck.
You know what I just now realized? Splendor, which is a terrific game, has this same mechanic. It's not quite a deck builder, but actually it is in some ways. The cards you buy get added to your collection of cards, which you can then use to buy more stuff. And one of the main tactical elements is knowing when not to buy available cards, because you don't want to flip over a new card for your opponent that might be the one you've both been looking for.
Ascension, which I do not think is a good game, has this same tactical element. There's lots of cards that let you control how many new cards are revealed from the center, and you want to use them wisely to avoid your opponent getting access to the better cards.
So I don't think that mechanic is automatically bad. It's just very different from the idea of Dominion, in which one of the best parts is the equal-access that everyone has.
Well, Splendor goes to great lengths to ensure that there are cards of varying values on offer at all times (by essentially having three different markets). Also, Splendor is a somewhat tactical game of point salading (nothing wrong with that), while Ascension (and Dominion) are games of infrastructure building, and there the unfair market hurts a lot, since advantages tend to grow exponentially, and asymmetries are far more prominent.
And thinking about that, there's also the fact that inefficient point sources and engine pieces hurt you much more in a deck builder than in a "regular" scoretrack game.
So yeah, mechanic is not broken (and it's as common as copper), but Ascension implements it badly to say the least.
(another example that makes it work is Power Grid, with the future/current market)