Loads of good points being made
In relation to DJing though, there's something about beatmatching which is integral to it. The fact that the tracks aren't perfectly in time just gives a sound to it which I love. And because the DJ is concentrating to get the tracks in time, it means they do the cuts and stuff more on impulse. Whereas if the tracks are already in time, the DJ is just a bit disassociated behind his laptop, and there's not that sense of urgency.