I'm not paying to see a DJ press keys on a laptop.
I'm with Stephen on this one. I love the energy of a live show, but I want there to be some sort of organic feedback between the performer and the crowd. I don't even think that's possible with prerecorded tracks. Nor do I care, because I want to see actual instruments, most important of which is obviously the electric guitar. Or a chick playing anything.
I give some of those guys credit because fading between tracks, remixing / manipulating loops in real time can't be easy. There are some guys that use stuff like synths and keys to add to the loops live no different than any other musician just with a lot more complexity and a lot more things that can go wrong.
I'd venture to guess the light shows are probably how they "liven" things up as there isn't going to be too much jumping around when playing with a laptop.
I'll give them credit for that. I won't give them money.
Too many clubs now hire DJs instead of musicians.