I just want an on/off button, a good panel, and a single HDMI input. The TV displays what comes in from the HDMI input.
From the searching I've done, apparently this is too much to ask for.
Where it becomes unavoidable is if you want certain features. Like my LG is the last generation of 3D TV, and one of the only TVs with Passive 3D on a 4K panel. I found that all 3D TVs were smart TVs, but if you're just looking for a panel, numerous brands will sell you a panel.
Also, note that smart TVs are only "smart" if you connect them to Wi-Fi. It's not like they have cellular radios. Don't give them Ethernet or Wi-Fi, and they'll do pretty much just what you want them to.