I think it's a case-by-case basis.
For things like debug rooms, they may be interesting enough and worth putting up.
I recall when we were mapping Super Mario Bros. 3, someone found an extra exit in one stage. There wasn't really anything to it, it was just an extra room. If there are unremarkable "scraps" of unfinished areas, I don't see much point to include them here on VGMaps, especially if they're inaccessible in normal play. Debug rooms like the one in Super Mario RPG may be among the exceptions because you can do interesting stuff in it when you do get there.
That reminds me...I never did get around to putting the second Bowser room in Super Mario Bros. 3 back in, did I? >_>