Digital Home Thoughts: Why Are There No Digital Cameras That Recharge Over USB?

We were discussing this issue in our forums a while back: why aren't there any digital cameras that recharge their batteries over USB like we do with our phone and MP3 players? It's a hassle having to remember to bring one power adaptor for my Canon SD870, and a different one for my Nikon D300. I can charge almost every device I own other than my laptop via USB so why not my digital cameras? I emailed a contact I have at a PR agency that represents Nikon and asked them to pass my question along. My contact was careful to point out that this is not an official Nikon Canada statement, it's just a personal opinion from someone working there. Here's the response I got back:

"I believe the reason stems from the power requirement issue. What I am getting at is that the typical user wants to remove the batteries to recharge them in a "rapid" manner, which cannot be afforded by a USB type interface. A cellphone is typically required to be available for use all the time which a USB interface charging method offers conveniently. Further a cellphone does not require as much operating current at any given time than a camera requires when it is in use."

Would you be willing to not be able to use the camera when it was recharging via USB? I sure would. I wouldn't even care if it took 200% longer to recharge via USB - I usually recharge my devices over night. I'm sure there are reasons why no one has tackled this issue yet, but unless they're insurmountable, I think the camera manufacturers should be looking very seriously at this problem - it would certainly be a differentiating feature that would set apart whichever camera was able to offer it first.