I feel like after a certain point, an epoch has ended. I know objectively, it's not just me, because there is a copious amount of proof..
At least for one: all the reboots and comic book movies, and Star Wars going down the shi*ter.
I do believe good films are probably still being made: just, not as many perhaps. The same goes for shows.
Real dialogue, good plots, good flow, character development... I think a lot has been lost. You can see it in music too. Compare to when the Beatles were topping the charts way back when, and compare that too what's topping the charts now.
Unfortunately, that's all a bit pessimistic, and it is also common, that, as we age, we begin to do that sort of thinking: "It was better back then!" and then shake our fist.
A lot of things were better, 'back then,' though. People used to be able to repair their gadgets. You could go to down to radio shack and buy some parts and build stuff, rather than this 'throw away,' culture that forces you to buy a new phone every two years, if you own a computer phone.
A lot of things were worse back then though too.
As for me? Is it an external thing, or an internal thing that keeps me sticking to the same old shows? A bit of both, I think. I know others though who, for example won't watch new anime, because it just isn't the same. And I don't even consider myself anywhere near old. And I know older folks, who totally have no problem being hip to the new jives of the day.
I think it's a bit of both, and it's circumstantial.
You're not alone. I'm rewatching stuff. I never used to do that. If I watched a show, that was it, never going to watch it again. And I remain like that for most shows. I rewatch star trek though, and star wars, if I can't find anything else to watch. I used to be able to rewatch certain movies over and over, but, I don't watch movies much anymore, though I miss it.