why do people say making shows ruined tv for them?

Everyone has their own opinion - I've worked in film/TV production for several years now, and still enjoy great shows. I still have a great appreciation for some film already out there, and films being made, and TV has always been on the lower end of that spectrum for me, but I got pretty hooked on "White Collar," for example. BUT, to answer your question, there are certain things I've noticed about how I look at a production since having worked in the industry:

I spend more time thinking about casting choices

I'm more likely to catch goofs, such as a boom mic in a mirror or something like that

I look at the process a lot more, as far as where the actors are probably coming from, how shots are framed, when they choose to go handheld versus sticks versus crane or jib

I badmouth large budgets a little more, knowing how much it really costs to make a decent film

NONE of this has ruined it for me, and most people that work in the industry LOVE other movies. If you don't love film, you shouldn't be working in it. Maybe it's more the TV people, I don't know, but that's just my two cents. I still enjoy losing (or finding) myself in a great flick.