Companies found out that they could produce shows with amateurs and cartoons much cheaper - hence all the crazy reality shows.
On another thread I posted the Best Picture winners from the last thirty five years that IMHO were worthy of the award.
In the 1990s 7/10 that were awarded Best Picture were truly EPIC Great movies. In the 2000-2010 there were four great movies. The last ten years there were a couple decent movies . Not great, but good movies. The rest were all weird artsy movies that NOBODY saw. Much less went to the theater to see.
The strike in late 80s made TV better.
Studios pulled out old plots and brought back Mission Impossible, Perry Mason and Columbo. And had the original actors if they were available or alive.