Yeah, you're right, and that's all there is to it.

I have worked for some years on modularity and standardization and e-waste cutting, and having a lot fewer power supplies and disposable batteries sure would help. USB is probably the right way to go for computing and telecom gear, since it exists as a standard and low power equipment is the way of the future. I would advise that as part of a general strategy of "healthy telecom"

http://hubley.org/green/telecom.htm
(lots of other ways to mature the industry there)

12V is important for fuel cells and solar power and replacing our 110-125-220V systems that need wasteful power grids to distribute power. The more you can do on 12V, the better. We should be charging cars with power at an efficient central generation point, driving them home, and hooking them up as 12V or higher supply to our homes. It is the most practical way to move hydrogen power, since pipelines are not a good plan, and neither is powerline transmission beyond the "gas station". Jeremy Rifkin talks about this a lot.

Probably biodieselectric cars must come first as the stopgap, though. These are already around... and they might also be good 12V power sources, and decent generators, but they aren't batteries.