I don't really need one, either, but then again, I don't usually *need* the winders on my film cameras, either. But apart from providing the more power, they add that handling convenience, (especially if there's anything like a flash or big lens on there) ...and your photos can always use the *ballast* for steadiness, even if your carrying shoulder might have a different opinion.
I'll see how long I last without wanting one. I'm taking bets.
Mine says three months.
(edit: Ah, now that I have my K20d, maybe I can hold out a while, this body seems to have a pretty appropriate amount of heft and is actually a great size for me, at least till something like a heavy flash might go on there.
(Also, for verticals when you don't have a vertical release, I generally advise going shutter-side down rather than having your right hand flying around over your head, ..not doing much good up there. It seems to feel a bit awkward at first, (For some it really is, depending maybe on your size: ) but combined with the right stance, that's usually the best way to do it if you can get a smooth release. It's good to learn both, though, so you can have a little more control over flash shadows, if nothing else.