splitstep: you're sooo right. looking at those videos, i can't imagine anyone saying that this type of practice is ineffective. i CAN understand someone saying they personally do not like doing it. but a wall cal help you rebuild a stroke, make a grip change, work on footwork, how you address the ball, height control, practice spin, practice maintaining a consistent contact point...
when you hit with someone, often times their shots are too inconsistent to allow you to concentrate on whatever you're trying to work on.