When wiil last party upgrade DLC will be added?

For me the only reason to have the party characters was to be able to achieve max rank.  I ground them out quickly and then forgot about them, for the most part.  I agree with your assessment, though I do know plenty of high skill players who do quite well with them.

Also, I'm a bit of a completionist, so that's another reason I wanted them.  Right now, the fact that I'm short over 100 FLF stickers and only average one sticker per 100-200K coins is quite annoying.