I know it's not easy to do so reliably, but if you were playing Spy, Scout, etc... and could do so, is it worth it? It sounds like it is according to you, and I would probably agree, but I wanted to hear from a few more players who are better than me.
I think the answer depends on how to interpret your question.
If you're asking, "Hey, I'm getting a bunch of Curses, is building a deck around Spy/Native Village to put them on my mat a good idea?" then I think the answer is pretty clearly no, that deck is too slow and too hard to set up and the potential payoff is pretty weak.
If you're asking, "Hey, I already have a deck with Spy and Native Village in it, and I happened to get a Curse, should I set it aside w/Native Village or get a trasher to deal with it?" I think in general the answer is probably not to get a weak trasher (and as Curse-trashers come it doesn't get much weaker than Develop). But then, why did you build a deck with a bunch of Spies and Native Villages in it anyway? What were you trying to do with those cards? As I said above, you don't want to build a Spy/Native Village deck just to deal with Curses, so either you're going to lose anyway, or you built that deck for some different purpose. What that purpose is, and the characteristics of the deck, determine the answer to your question.
It may be more helpful to consider an example. Let's say I'm building an Apothecary/Native Village deck, and there's a Develop on board. Ordinarily I wouldn't buy that, because it doesn't go with the rest of my deck. Now let's say my opponent manages to give me a Curse. Should I put it on my mat, get Develop to deal with it, or ignore it? I'd say the answer depends on the stage of the game and the nature of the Curse.
If:
- early/mid-game, got Curse via Swindler/Jester/some other not very consistent Curse-giver: put it on mat along with Victory cards, since this is a minor speedbump and I will rely on my deck's superior speed to win the game.
- early game, got Curse via consistent Curse-giver like Sea Hag or Ill-Gotten Gains: buy Develop, punch self in the face for picking a strategy that is going to fail hard against Curses, look for better strategy to transition into
- mid game, consistent Curser: the only consistent Curser I can think of that wouldn't start giving Curses until the mid-game would be a multiple-Torturer engine, in which case I think I would probably get a Develop since a) there's a much better chance I get some shuffle where I only have $3, b) since the curse is in hand I'm much more likely to be able to draw Develop and use it on the Curse, and c) I need to make sure my deck doesn't get clogged by Curses before it gets going
- late game: ignore and draw through, putting VP on mat as usual, since the game will be over soon
So...yeah, I guess what I'm trying to say here is, if you get the opportunity to put a Curse on your NV mat, and you know you don't ever want to pick up the NV mat, it's usually the right move to get it out of your deck. However, it's usually not the right move to build a deck that can consistently do this.