I laugh at people buying 4K TVs… your eyes are almost certainly not good enough to tell the difference in the vast majority of viewing scenarios. Total waste of money
If we were just talking about the absolute resolution, you are right. At my normal viewing distance I can’t tell the difference between 720 and 1080. I’m certainly not going to see much improvement from a 4k screen. But it isn’t just the resolution. The more pixels you have to display the image data, the better the image looks. The pixels start to disappear and be truly invisible. I’ve known this about printing for years, but when you apply it to video, it really helps the realism of the image, even if you are watching a 480 DVD. With the proper hardware, everything will look better on a 4k screen, even if you never get a UHD player or media.
My dad has a 43 inch 4K TV and DVDs look horrendous.
It definitely varies by TV. Rtings.com has an SD category in their ratings, and some 4K TVs do a fine job, while others are pretty miserable. It also depends on the DVD player, of course. Something with composite output or a PS3 via HDMI? etc.
Even blu-ray can look terrible on the newer TVs if the settings are all cranked up to eleven.
A little over a year ago I was at a Best Buy where they were playing Captain America: The Winter Soldier on a 4k tv (it was an lg lcd iirc) with what must have been the out-of-the-box settings. It looked truly horrendous.
Oh, absolutely. I’ve got friends who are completely ignorant about audio/visual types of matters. And some of them will say that they “hate HD” because the picture looks terrible and unrealistic. I’ll ask them how they feel about the picture quality on their 1080p laptops and in movie theaters, and of course they think it’s great. But they’re familiar with HDTV meaning shitty interpolated motion, oversharpening, and the host of other features that people will turn on (or, often are turned on by default).