It was the actor not the character.
He was an excellant pick for the role of Capt Picard....
Well he actually saved the show from the bad HAMMING of Gates McFadden and Marina Sirtis in the first two seasons.
When they mellowed out the show really took off.
Yes, it was the really terrible acting of the supporting cast that allowed him to shine. The worse they were, the more perfect he was.
How many characters could have been recast or even eliminated without harm to the show?
Yar - well, we know the answer to that one...
Crusher? They had another Doc for awhile and the show worked.
You could pretty much rewrite, remix, or eliminate any of the supporting cast and still have had a solid show.