There are two issues here, the fragmentation of the services, and poorly implemented services.
I have really really tried to use Google Play for video because it seems to work on the broadest array of devices, but the service itself is a second rate experience. Too many clicks, laggy unresponsive UI, silly JS driven pages that require reloading in order to start working again...
I too really want to do things the way that supports content producers, but the middlemen are doing such a poor job that it's difficult to get my money to them.
I don't know why Google doesn't make any effort to tell users this, but: you can access all of your Google Play video through YouTube. Just search YouTube for the thing you bought, and you should find the full-length legal video marked as "purchased" that you can watch with YouTube's interface, casting and all.
We rented a movie on Google Play and this was literally the only way we could watch it. It didn't even show up in our library on Google play. I have no idea but I was just lucky to have thought to check YouTube as well.
Another sub-aspect of the poor implementation is oppressive DRM and player restrictions.
Netflix and Prime are finally acceptable on Linux thanks to Pipelight but that solution's not for everyone.
If you want a single settop box, you might run PI with XBMC/Kodi but you can't get DRM'ed things on there. So you need a Roku or AppleTV for your DRM, a chromecast for things coming from a PC, and you still need a Kodi for your personal needs.
There's a lot of fragmentation, but things are getting better. You can do all that with a FireTV stick for $40. It runs DRM apps, has a Kodi fork MrMC in the store (or you can sideload Kodi), Miracast for general screen casting, apps for other casting protocols, a YouTube app for Google content.
Against Balkanization, Fan.TV and other guide apps combine all your streaming sources and antenna TV into one. And everything can be controlled from your phone.
There's still room for improvement, but we have it pretty good. The biggest problem is figuring out what hardware and software you need with all the options out there. We're just spoiled for choice.
This is what I use, and I love how responsive the Amazon FireTV remote is. I have the FireTV hidden behind my TV and the remote works from anywhere in the room regardless of if I'm pointing it at the device or not.
Now they use a accelerator/gyroscope and a dedicated RF channel to provide input. Plus that you can transmit also more data ( Wii remotes send the battery status too, for example ).
I have really really tried to use Google Play for video because it seems to work on the broadest array of devices, but the service itself is a second rate experience. Too many clicks, laggy unresponsive UI, silly JS driven pages that require reloading in order to start working again...
I too really want to do things the way that supports content producers, but the middlemen are doing such a poor job that it's difficult to get my money to them.