The unions killed the variety show. With HD TV it would be a great time to bring back the big dance numbers, but the costs to rebroadcast are prohibitive because of the dancer's contracts. That's why the old Carol Burnett show only has the comedy skits when it shows in reruns. The standard contract requires that every time the show is rerun each dancer gets paid not only for dancing, but for rehearsal. Since much of the profit from shows now comes from reruns, the dancer's contract effectively killed the variety show. Also, variety shows have never drawn ratings in reruns like comedies and dramas. I think variety shows are more tied to a specific time and don't age as well, although musical movies like Oliver, My Fair Lady, and the Music Man seem to stand up well. Possibly because they're period pieces. I'm not sure how Disney worked it out with High School Musical.
Rosie, like Sandra Berhard, has stayed on television etc., because of the gay mafia running entertainment. Neither of them has ever drawn significant ratings, except when attached to a project that would have been successful anyway.
I do have to admit that there is a car-wreck quality to a Rosie performance, but like Britney Spears, it's become old hat.
I enjoyed the Carol Burnet show - My favorite was the Dean Martin Variety Hour...Dino with a cocktail and smoke in hand, the “Gold-Diggers” in the background...Loved it.