I hate the flexicolour system with a passion, it was clearly an afterthought and never well implemented. There is a maximum of four slots per object to begin with, which is already limiting. But the selection of which areas of an object are colourable with which slot, and what is colourable at all, is arbitrary and inconsistent. It feels like there were no good guidelines or even quality control regarding this subject; Like the availability of flexicolour depends on the skill/ mood of the designer responsible for that object.
I can kind of understand that the "old" assets from the alpha (before the implementation of flexicolour) still need to be treated and this is an ongoing process. But forgetting the colour options is unacceptable for anything recent, especially now that we are supposed to pay for the assets.
How hard can it be to put up a memo that everything should be colourable, unless there is q very, very good reason not to allow it? Anything that is not complying to this rule should be send back to the drawing board, unless the designer can convince the person in charge that the object should really be only available in the colour he or she had in mind.