I happen to disagree. I don't think it adds excitement, but I also don't think it kills the show, necessarily. I find it very annoying in procedural crime shows, which has the cop and the non-cop specialist team up to solve crimes. (If they're the opposite sex) then it's almost a given that it's going to happen, and that's just too obvious for my liking. Don't get me wrong, I have nothing against it as such, it's just the execution which I find lacking.

As for post hooking up, it does need to be handled correctly, otherwise it just stagnates.

I don't know about it killing the show but I always root for main characters to hook up if they seem to have chemistry. It's like they'd be so good together in real life b/c they look so good on screen kind of thing.

If they have really good chemistry I think it's alright, but sometimes they do it and you just wonder...why?