It is important, but to a point. After that you're moving yourself and your weight, but need to move it as fast as you can. Grinding will increase the number of motor fibers you can recruit, true, but in most sports power is valued.
I saw oberst mention safety and I think he's off, because you can snap your shit on a bad clean too, but there is something to be said about the fact most d1 trains using cleans more than deadlifts. Bugenhagen's approach aside.