To the question, I can answer quite briefly: No
Ok
And now less briefly: If impact is defined as something that will keep a majority of people playing and interested in the game, the answer is no, I think. Some people, particularly people like us, roleplayers, but also others, will like it to varying degrees, but the commercial success of a game seems to have no connection to whether there is ingame events or not. It is not on top of most players wish lists, nor are there that many participating in the few events that are held.
Also, events are a strange thing to handle to everyone's satisfcation. Are they IC only, RP'ed out? Then everyone but the few RP'ers will find them strange, and most will avoid them. If they are general, OOC events, then more people might find them cozy, and they will attract a bit more attention, but their point will be kinda' lost, the RP'ers would revolt, and in any case I don't believe they would have an impact.
But, not to be all doom and gloom, I'm just trying to look rationally at the question. Of course I'd like RP ingame events, the more the merrier, in all MMO's, but realistically, they won't matter in the big scope of things, i.e. commercially. They might however heighten the reputation of the game in the RP community, and draw more RP'ers. SoR had such a reputation once, and even non-RP'ers listed the ingame events as a good aspect of the game.
And events are a bit 'in the middle', in that the game itself should provide the content/events, or on the other hand, the game should be completely RP, like Seed was, not just with 'events' thrown in here and there to liven up the desert. Still, events are a plus in my book. That just won't net any company much money I'm afraid, though it will heighten the quality of the game as I see it. The general mass of gamers wouldn't care though.
My, I'm Mr. negative today And it wasn't meant quite like that, just giving my 'objective' view about what kind of impact events would have. They can add colour, but for the non-RP'ers they're irrelevant and for the RP'ers they're not enough. Tough place to be in ;D