They're aesthetic in that they're a matter of taste and don't have any objective impact on the cue's performance.
pj
chgo
I agree with alot of what you've said above Pat, but if these "matters of tastes" effect the "players" performance then they are important. I've never seen a cue hit a ball with out a player moving the cue. I think we must always consider the player when talking about the performance. As an example, in golf, I play with longer clubs that have longer than standard shafts. Although a standard shaft Ping club may be a "higher performance" than my Dunlop club, I still play better with a longer club. My assertion which you may disagree with, is simply, If something about the feel/sound/vibration etc. of the aftermarket LD shafts (Predator, OB1 etc) bothers a player to the point of reducing their performance during play, then the after market LD shaft just isn't for them.
I've played with both LD aftermarket and the shafts that came with my cues and I still prefer the standard shafts that come from my cue makers, though they are not really what I'd call high deflection.