MC does have television:
https://wiki.jriver.com/index.php/Television
It's on Windows, not on Linux or Mac.
Try Escape to exit. Or use right arrow to the end of the home view.
Escape gets you out of the theater view. But it's full screen in standard view after you get out of it. And the button to change the size no longer works. Minimize works and exit works. F11 would be a hotkey to maximize/minimize usually everything that supports it. But it does not do it either.
Nice try with the television, but I have a TV, because it's a big screen you can actually buy, not because it can play television.
So, personally I do like plex for the netflix like experience and it having apps for just about anything I use (that are pretty good, although not perfect) and a great webui (that is again a lot like netflix). But it does absolutely fall flat on it's face for music!
I never actually used it for music, I tried didn't like it. If I had to weight the amount I care about things I'd probably say I care something like 75% about music and 25% about movies, shows and so forth. So, I'm not really going to ditch jriver anytime soon unless something better (for music) comes around.
Before JRiver I used MusicBee... So that didn't work out anymore very well when I switched to to mostly (but not exclusively) using Linux. And it was a mess even before that. Syncing things from PC to PC is something I absolutely wanted to avoid. So here I am, now.
Plex... well unless you're going to outclass it in every way. It's a one time purchase. it does not cost me a penny to continue to use it for watchable content.