From Aristocats (the first post Jungle Book film) to Beauty and the Beast, most of these films have had a full frame release on DVD. Usually in the Gold Edition. I've noted most of them in the first post.
If I missed any, you can check out editions here: http://www.dvdizzy.com/disneyanimatedclassics.html
I believe from Fox and the Hound on, Disney started moving back towards natively wide formats.
As far as Beauty and the Beast goes, 1.66:1 (the OAR) isn't that far off from 1.77:1. Yes some image is lost, but not a lot. You're talking about 3% each side. You lose more than that in overscan.
Heck, a lot of films lose that just in the transfer process. For example, the Jungle Book full frame version SHOULD be everything animated, but the widescreen release, while cropped at the top and bottom shows some image on the sides not present in the 4x3 release.
It's not technically pan and scan, just sloppy work. This isn't limited to Disney, a lot of studios do it when transferring films.
I wouldn't mind seeing a screenshot comparison of the LD to the PE DVD showing how much is being lost or gained.