You got realy good points in your post ... Slash's solos rule man, and are very hard to copy although they're not fast , and no sweeps or crazy techniques anywhere ... Beautiful guitar playing is mainly dependant on the mind , not the crazy fingers and picking styles.
And yeah , playing some GnR , zeppelin , metallica is more fun than just trying to copy Malmsteen , start a Neo-Classical band & be his next clone.
But this doesn't deny how usefull new techniques (like sweeping) are ... New stuff that could have never been played before on Guitar , now could be played easily ... Just to add, not all shredding lacks soul and beautiful phrases .
Sweeping , tapping ,etc. are just tools to enhance the music or allows to play notes that can't be reached normaly at a certain bpm ... one should not just focus on raising the bpm into max in his songs cuz every song has a certain bpm that suits it most.
Raising the bpm to max is just for practicing , little showing-off at guitar breaks between songs onstage or impressing your friends , and should never be the goal for playing every song.