I think I'd play more gigs if it was acceptable to just sit in the corner with a laptop plugged into a PA.
i guess this isn't acceptable because the purpose of a gig is to entertain people and give them something they can't get at home, not to fulfil the "performer"'s egotistical desire to Be A Gigging Musician or to Have Played A Gig
which is why i chose to decline invitations to "perform" at events i have been asked to "perform" at
i have said it before, if you are gigging you are an entertainer. make sure you entertain people (OTHER people, entertaining yourself does not count).
edit: i feel the same way about busking. if people using a certain street or public space don't want to hear your music, it's selfish and inconsiderate to force it upon them.