I'm not opposed to backing tracks at all, if they bring more to the song and show. B. tracks, loops and triggered samples are just fine in my books. However, I don't like a complete playback gig (which the OP's situation seemed to be), unless we're talking about dance music performers such as Britney etc.
I play original industrial rock in a 4pc group. 99% of our songs have a backing track (multitrack, actually) coming from a Zoom R16 which is controlled by our drummer. On releases, we're mostly electronic (NIN-esque, I guess), but live we add guitars, drums, bass, live synths & sample pads etc., which brings in the "rock". If we didn't use backing tracks, we'd need 2-3 people more on synths to play the alternate harmony basslines, sfx, pads etc. Took a while to get used to it, but it works for us. Can we play the songs without the backing track (say, the Zoom crashes)? Yes, of course, and we'll still be good. Will it be a better show/experience for the customer with backing tracks? Probably.
Here's what our people do live:
BL: Vocals, guitar, 2x synth on some songs
2: Lead synth & pad, add. guitar
Me: Main basslines
4: Drummer, controls backing tracks/Zoom R16
From the backing tracks:
- click for drummer (pro guy with good time)
- multiple pads
- alt. bassline from synths
- backing vocals (on one song)
- sfx and other funky sounds
- interlude loops between short breaks
Can't really relate to the whole "omg karaoke" -ragething a lot of people seem to have going on here towards the use of backing tracks in general. As long as having the tracks benefit the song, fit the style and don't cause disruptions/unnecessary breaks between songs, all is good.