I'm imagining it either as an addition to the randomizer tool because that can already humanize note properties like velocity or as a separate tool which could be quicker to use.
It will let you randomize start and end times/duration of notes randomly as well as how the randomness is applied/aligned (tension, added or subtracted/dependent on note length for example).
I think fl's piano roll smashes all the competition and this would make it even better.
