A lot of DJs just feel more comfortable on CDJs. Look at Laidback Luke & Armin Van Buren. CDJs became the club standard before Serato, Ableton and Traktor got really reliable. A CDJ is similar to Traktor LE but all laid out with giant buttons. It has limited cue points (3 hot, 1,000 CUE per disc), wave form display, BPM display, CUE, CUE/PLAY, key lock and pitch control. Since all DJs could agree this was a great setup, it stuck. The problem with laptop DJing is that there is so much personal preference with software and hardware. I can DJ the same on serato, traktor or CDJs so I dont' care as long as I get to play.