The heading of this thread is very confusing. Do you mean to ask what shows should have new recordings? Once on This Island has a London Cast recording as well. I'm not sure why there needs to be another as the Broadway recording is pretty much complete and I don't see how it could be improved. Same with Rent. Beauty and the Beast also has London and Australian cast recordings, so any more in English is unnecessary. Merrily We Roll Along has the Broadway recording, Off-Broadway revival and London recordings (of which there is a 2 CD complete recording) that are pretty much identical to the new version of the show. The Secret Garden has a highlights recording from the Australian production and a London recording featuring a revised score.
As for shows being revived, Once on This Island is an excellent choice, but I think it is a bit too soon. If you've never seen it staged well, then it's hard to get why so many love it. The score is beautiful, but the original staging was just wonderful. Every scene was brilliantly done with little to no sets at all.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian