If they're ignoring the 68k market then that's their problem. There's no reason you can't hire some developers to produce whatever updates you would like for OS 3. You might even be able to get Cloanto to help out - they've already shown an interest in updating the OS by releasing the 3.X kickstart, so maybe with more support they could organise a release 3.10 or something with support for RTG, USB and all those other things we'd like. If the market for such an update is 100 times the size of the OS4 market, surely they'd have no problem making back the development costs.
I'm all for OS 3 updates, but I'm really not sure why the lack of advancement is the fault of a company who choose not to be in that market. With that thinking maybe we should blame Microsoft too - after all they're not doing anything to update OS 3 either.