The original concept was great for some things, sure.
I bought an OG Chromecast over a decade ago. It was a one-trick pony: Push "cast" button on pocket computer, and whatever I was doing there would show up on the BFT.
Which is great, you know, for a person who lives alone and never has visitors: One can select an item from the slick interface provided by the service they subscribe to on their amazing personal computing device and it appears magically on the big screen. The control buttons are there on the pocket computer, too. It Just Works.
However, it is an awful experience for someone who wishes to watch a film together with others: My personal pocket computer is not really set up to be shared with others (and the live screencast function of Chromecast, while functional, has really high latency for interactive tasks).
And if someone else wants to pick something to watch using their own personal pocket computer, then they can of course do so -- but theirs is also not meant to be a shared experience, and they won't be able to use the services that I pay to use in my home.
So fine. A film is selected, however that is done, and it is playing. But it's time to pause it so someone can use the bathroom. Do I use my phone for my Chromecast for the movie my friend picked on their phone? I already had to hide the buttons from showing up in the notification area of everyone's pocket computer on the LAN, since my roommate kept being a dick and stopping my shit.
Or do I have my friend fumble around with this potentially-unfamiliar interface on their own (locked) pocket computer to pause it? What if they stepped away? Do I find the Home app on my own pocket computer, open it, find the devices page, find the appropriate Chromecast device, and then finally fucking pause it? (Fuck you. I just want to go take a fucking piss.)
Back then, it was a much better experience in my household to use a PS3 for streaming: It had a regular remote control that -- as a design intent -- anyone could pick up and operate. Browsing possible selections was done on the BFT that was visible to all interested parties. My roommate didn't get a notification on their phone that encouraged them fuck with me from a different area of the house. It was a much better experience for those who didn't live a life of absolute solitude.
Today, it's still that way -- except nowadays I have [what is sometimes referred to as] a GCWGTV. It can behave like an OG Chromecast (what UI???), or it can behave like a human-centric streaming device with its own GUI and dedicated physical remote control that anyone can pick up and use, browsing Netflix or Plex or whatever in a manner very similar to what we were doing on a PS3 back in the day.
This works fine.