MTV has NOT always sucked.
The only valid argument that MTV has always sucked is that all of the radio music over the last 40 years has sucked.
The radio music of the last 40 years has been worse than MTV from the beginning of MTV 82 or whenever that was, up until maybe 2000-2005.
When MTV pretty much became 20 year old sitcom reruns and reality shows, they stopped breaking anything interesting. MTV did a much better job of finding the best rock and playing it a lot than radio stations did. Our rock radio has been much worse over the last 15 years than it was the 15 years before that. The 5 years from 2000-2005, MTV was clearly going downhill, playing way too much of the boy bands and that kind of stuff, but they always did find some fresher rock, and occasionally radio stations would pick up on that.
If you want to argue that the world of rock was actually better without any successful bands, maybe you're right, maybe, but MTV when it was trying to find rock, did do a better job than radio did.