Do we need them remastered though? I know I'd like having one Blu-Ray disc with an entire season on it?
I suppose that could be done. But the viewing public wouldn't go for it. People expect the content on Blu-Ray discs to actually be in HD.
There's no disc/set that I'm aware of, that does what you mentioned - using Blu-Ray strictly for storage capacity (i.e. fitting an entire season of SD content on one disc), although I assume it is technically possible to do so.