Not to mention, unlike a hand job or even , no one can replicate the sensation of a blow job on their own obviously.
Back to that visual thing from the previous point.
A huge factor of a blow job is the visual component, Marin and Anderson agree—presentation is everything, people! Asking for feedback shows that you care and want to give your partner the best experience possible.
While everyone has their own, ahem, moisture preferences, I've found that most agree a good blow job requires a lot of saliva.