+1
John Randolph played Roseanne's dad in about two episodes early in the first two seasons, and then never appeared again. Debbie Reynolds appeared about once in the (best forgotten) last season. Both of their characters would also have most likely have passed on at this point anyway realistically; same with Nanna Mary.
Glenn Quinn is the only issue of any real merit. I don't think it necessarily needs bringing back, but on the other hand they could at least give it a better ending that what it got originally (and they could hardly do much worse!).