(edit: or maybe you meant that most people bought their TVs a while ago and never upgraded?)
Hope this helps someone!
But I'm a weirdo and I don't even have the TV set so that's that ;-)
You just want the hard inputs? what about the built in tuner? where and how does the sound mix? Output ch2 sound to a different external speaker and use the internal for ch1? etc.
Nobody really wanted it to the point of figuring out how to use it, or coming up with a control convention that spread to other users. For so many uses where "PIP" is useful, a 2nd display is much more useful, easier to set up and use, and more likely to be replaceable.
Next question is "What about 3D TV?" ... Many mature industries go through these cycles of marketing bullshit.