No, but it certainly doesn't hurt.
Playing fast, complicated skill and the like is impressive, but there's more to being a musician, or an artist, than technical skill. Any music or art of value that is of the highest degree of quality should make some sort of statement. And that can be done without technical mastery. Look at early punk rock... not much technical skill there, but obviously a lot of great musicians who changed music while making "grand" statements about what music is.
Again, there are certain musicians who have that "total package" which I alluded to in your last thread, and those are the musicians who are in the upper echelon.
Having great technical skill makes it a lot easier to experiment. It makes it easier to express yourself. But it also can become constricting and the music only becomes about showing off technical prowess. It becomes empty. In these sorts of discussions, I've seen the name Yngie Malmsteen thrown around. Obviously, a great technical guitarist... but what else is there to his music besides "holy fuck he can play fast" and "holy shit at those chord progressions." Which, as I said... is impressive, but it kind of ends there.
Then you take a band like Suicide, who didn't even know how to play their instruments... and they made some of the most beautiful and thought provoking music of the last 30 years.
I'll bring up the artist Jean-Michele Basquait.
From a purely "technical" standpoint, at least in the traditional sense... he can't draw.
Or he chose not to.
But I'd say he is way more of an "artist" than some "realist" who just paints things that look exactly like a photograph, which may require more technical skill... but where's the creativity in that? What ideas or concepts are being expressed? Basquait's work is far more expressive and interesting than say... Norman Rockwell. Because it says something.
And hey, like he said... he can draw. So maybe he had technical mastery which made it easier for him to express the ideas and concepts that he wanted to. He had more tools at his disposal so it was easier for him to explore than someone who was less technically inclined.