The software on TVs I've experienced is universally awful, my parent's one is particularly bad - you can go and make a cup of coffee in the time it takes for the Netflix app to start. When I heard that I bought them a FireTV stick and haven't looked back.
TV, as pretty much every device, should be as dumb as cables .. must be reliable and work with pretty much anything that it's plugged to, no matter what that is
I have a nVidia Shield TV plugged in to my 4K Smart TV that I do almost everything on, but I still have to use the smart TV app for Amazon Instant since Amazon stubbornly refuses to release it for stock Android.
For Samsung TVs the SamyGO project can do some stuff - http://www.samygo.tv/ - but it's more about hacking the existing firmware than making an open replacement.
Oh I also think TV's should all be about we glamouring for the resolution. Seems 4K is here to win.