Do you mean those movies are filmed in 4:3, or the only home video/nontheatrical release available is "full screen"?
Some things are supposed to be "full screen".
That's actually a misnomer--for a widescreen tv, what was FS is now no longer "formatted to fit your screen."
So, some things are meant to be 4:3, and are filmed that way. I think a lot of older Troma films were. Perfectly ok to view those in 4:3 or "fullscreen", you're not missing anything.
Widescreen [ie, any aspect ratio wider than 4:3]; 4:3 ["true" fullscreen], and P&S, where they take a widescreen program and either pan and scan or zoom/crop to fit 'most' of the image into a 4:3 box.
Anyway. I don't buy pan and scan. I will buy 4:3 if that's the intended ratio. I buy widescreen if that's the intended ratio. Have ever since I realized what the difference was, even back on VHS.
The 'black bars' aren't really there, they're the absence of image.
I remember Roger Ebert saying, If you focus on the black bars, it must not be a very good movie. It was on a 'widescreen home video' episode of At the Moies.
Check out
www.widescreen.org for some very obvious screenshots showing why Widescreen is superior to pan and scan.
And just to toss another monkey wrench in the mix, if I watch 4:3 content on my widescreen TV or through my SDVD player, I usually stretch it. Not because I don't like the 'black bars' aesthetically, but because I don't want to risk burn in. And I'm still seeing the 'whole image'. If I watch on my hDDVD player which upconverts, that doesn't stretch, so it's 4:3. However, I try to save 4:3 content to watch on the computer or the upstairs (4:3) tv.
In the case of pan and scan, the "story" may not change, but the interpretation of the story may change. You may miss things that were there in the OAR version.
Check the 2nd and 3rd examples here
http://www.widescreen.org/examples/labyrinth/index.shtml
The WS gives you a much better view of the immensity of the labyrinth.
And example 4, oh, there's two characters talking. Example 7, oh, he's chasing her, not just standing on some stairs
http://www.widescreen.org/examples/musicman/index.shtml
Example 6, what is that, a barbershop duo? Example 8 you're definitely missing something, the scene was a compare/contrast between the two groups of people.
I guess according to your logic, 5.1 or other multichannel audio is "totally nonessential" in 99% of case, but I sure don't want to give it up.
Hell, in most films color is not really necessary for the story.