there are no broken promises here. the current implementation is only temporary, which has always been the plan with mt. rainier. it's not until the next version of windows that mt. rainier will be natively supported by the OS, unless microsoft releases an update for current windows systems.
also, an "INCD formatted disk" is not what's necessary for mt. rainier to work, it's a mt. rainier formatted disc. incd is not the only software that can currently read mt. rainier, so someone who doesn't own incd can still read the discs using other software.