As stated by Mxx it would require major changes to the design of FlashFXP. If not a complete rewrite, a major rewrite. FlashFXP is developed by myself, a single person, where as CuteFTP probably has a team of developers working on CuteFTP. Simply don't have the time to add every single requested feature. I wish I did.
Who says FlashFXP has all the features? I've never said that. I feel you should use whatever ftp client suits your needs.