My parents Samsung smart TV has been gradually downgraded over the last 2 years and my old Now TV box has been auto-updated to the point that input lag is about 10s. This is something that had always put me off having all this functionality in a single device... do one thing and do it well.
Thankfully I still have an Android TV box which handles "smart TV" functionality... for now. Though it's still only a matter of time until the apps require updates to continue working and further down the line those apps will no longer be available for my version of Android. That will either be a night following guides on xda developers unlock bootloaders, flash recovery and roms etc, or charity shop/bin and buy new.
Manufacturers need to take more responsibility for their devices to ensure a longer functional life and reduce waste, even if it comes at the expense of new shiny things.