I have often wondered this, although never mentioned it for the reasons you listed above. I have a toy, which uses some demented form of miter gears in a shifting transmission( i think they call them crown gears. Legos have them too.) Anyway it looks like this:
Please excuse the paint art. This design is probaby impractical for a number of reasons, but none the less i think its interesting. It inspired this:
Its probably still impractical but whatever.