i have a feeling that those purists are not necessarily put off by bass guitars in general, but are offended when bass guitar is used to substitute for an upright in musical contexts where the upright sound and feel is an integral part of the music. There are certain things a bass guitar can't replace an upright for, and vice versa. But you don't come across the "vice versa" situation very often except maybe in rockabilly bands doing rockabilly versions of rock songs that originally featured bass guitar; on the other hand there have been thousands upon thousands of TV commercials, muzak renditions, etc. where classic songs from the swing or rockabilly eras are redone in a lackluster way with obvious (and too-often rather wimpy-sounding) bass guitar not even trying to sound like an upright. I'm a fan of both instruments, and each one has its advantages and disadvantages in different situations. If I go see a retro swing or rockabilly act, i will most likely be disappointed if they have a bass guitarist, unless the bass player has taken great pains in trying to get an upright-ish tone via string type, EQing, muting, and playing technique. I've seen it done before, most notably the bass guitarist from Simon and the Bar Sinisters playing his Danelectro Longhorn in an upright slap style and it sounded very good...
