Many years ago, before things like Youtube or even VCRs, clip shows were actually pretty popular (well, assuming they were decently put together). It was really the only way, other than catching a rerun at some odd hour, to see some of the show's best and most memorable moments again, and like a "Greatest Hits" album people liked them even if there really wasn't much of anything actually new in them.

Nowadays of course they are pretty much obsolete.