Too much TV is a BAD thing in my humble opinion, but I don't get the 'evening only' thing.... I rarely watch TV in the evening, I'm doing other stuff.
Weekends in moderation, seem fine. Some Action films aren't suitable for children, some a fab (Star Wars is fab, end of) and we often have film days on lovely warm sunny afternoons...
Too much of anything isn't good for you, but being inflexible isn't good for anyone.
I think YABU to a certain extent, in that you're inflexible. YANBU to think too much TV isn't good though.
The TV is off at present in our house, the kids are in the garden, the husband is watering the vast amounts of bloody plants (that's another debate seeing as its me who has to keep them alive when he's working away) I'm cooking and listening to (forgive me) Rock FM. If anyone wants to watch TV between now and 'eveningtide' then I do not mind. I like TV though, I love films, my kids know the difference between fantasy and the rules of real life, they love films too and have active imaginations and fill 'bored non techno' time very well.
Balance, moderation, and flexibility in my opinion, are key to happiness an health. My kids are not allowed to watch Snow White as it upset them a lot, they can both watch Transformers One, Star Wars (all of) on the condition that they understand that they cannot turn into a big gun or use real lightsabers on anyone.