After playing with Villa a few times now, I think it's key that you're making the most of the turns you buy it on. If you buy Villa for $4, and then play it, play another action, and then buy something else, that action you've played and extra card you bought need to have been worth it.
Example: I buy a Villa, play it, and then play the Smithy I couldn't play before. If I only have enough money now to buy a $3, maybe I should've just bought some other better $4 instead of Villa. Of course, I've also cycled 3 cards, so that's a + too. Or maybe the extra action I was able to play was an attack, that's worth something. Or maybe I played a smithy and drew my trasher. Well, I don't want to miss trashing this cycle, so I'm going to buy a Villa so I can use it (hopefully I still have enough cards in hand to trash).
To say Villa is a bad card because it's basically Crap Festival is like saying Border Village is a bad card because it's Twice as Expensive Village. In both cases, there's a lot more going on. I like what Mameluke says about Villa being almost an Event, you're buying it more for the opportunity to get more out of this turn.