My big problem with learning Dvorak is that once I was accustomed to it I suspect I would find it very difficult to use qwerty keyboards, and given that they are standard and hence I have to use them fairly frequently on machines other than my own it would impose excessive costs. (Though if theres a way round this, other than carrying a keyboard everywhere, I'd be interested to hear.)

As for the general lack of optimisation, I suspect every individual user/manufacturer has no particular attachment to qwerty but there is a general benefit from having a standardised keyboard however good its design is.