This has indeed been suggested before, and while we're not closed to the idea there are various things for us to consider.
Each recolor is actually a brand new hat in itself, and each file weights and takes time to work on, thus we don't want to spend our time/space on too much recolors, we prefer to add unique looking hats. But technically it's quite possible, and a player has even made us some nice recolors of FB, it's possible we may add some eventually.
We also have other nice looking hat with similar stat, take a look at the brand new elven hat (obtainable from woe participation).