I've watched SNL since the first season. I think you may be looking back with rose colored glasses. There were plenty of bad sketches then, too.
That's why I was a big fan of SCTV. They had some off shows, some off skits here or there, and a few off transition periods with different network formats but by and large the episodes still make me laugh from start to finish. I read Dave Thomas's book on the whole production and it was quite a story. Stuck in the Great White North with little budget, no distractions and virtually no network oversight. Just go out and make some television... The Great White North segment, which Thomas and Moranis were actually a bit embarrassed about its success (compared to the rest of the work), was apparently added to meet some CBC requirement for "native content" so they created two beer swilling, semi-dimwitted hosers to represent Canada
