Benoit - here, here. Another big difference (along with your points) is - speed is impressive to other guitarists, who buy about 5% of the marketed music. Gilmour appealed to the masses with his melodic riffs and solos. It comes down to the all mighty dollar - if you want to get rich, the speed licks aren't going to cut it. Satriani, Vai and Yngwie have all had troubles marketing their stuff over the years. They're great - but in a very small arena.