I hear what you're saying entirely. At the same time, think of the bar just below the kneecaps, and the bar from the floor. It's still a very functional lift, and the little bit you're missing out on doesn't seem like it'd make much of a difference.
The ROM lost would be similar to doing a sumo-deadlift, I would think. For shorter guys, from the floor probably isn't a problem. I'm 6', and deadlifting off the floor definitely bothers my back. The part of the lift I'm looking for is the stuff that happens just a bit higher.
Also, just because you don't deadlift from the floor, doesn't mean you won't be able to do anything in that small ROM. You don't directly train every athletic movement, but you still perform in all of them and that performance increases as your lifts increase.
I dunno, maybe I have no idea what I'm talking about. I'm running in overdrive now. Too tired. Gonna go pass out. I'll feel more coherent in the AM...or PM...whichever.