I just heard the TLOS demos for the first time yesterday. Out of curiosity, I was trying to figure what purpose these demos actually served. They sound way too embellished and extensively worked-on to serve as just a rough reference demo. These aren't "Brian alone at the piano in 1977" type of demos. They seem almost like a version of the album that was rejected, and then started over from scratch, ala Sweet Insanity. Any thoughts?
They are definitely demos, just (as you properly say) not the "singer-at-piano" sort. People frequently do fleshed-out demos in order to save time and money in the studio. It allows you a (free or cheap) opportunity to consider how more parts will work. That way when you get to the studio that costs money, you have everything mapped out and just do it, as opposed to fiddling. While Mr. Wilson had his day when such studio time wasn't an issue for him, I'm sure he and his team would rather not pay for experimenting anymore.