At first, I thought it was OK even if the delayed MS bonus threw me off (at least it's .25 seconds longer). However, it's basically doing nothing except helping you kite once the game is past 30 minutes (only .10 BONUS AD scaling). It's in the same tree and has a very different purpose from each of the others but rather than being a choice of sustain/kite, it's also a choice of "are you OK with no late game viability?" I'm guessing they don't have a better ratio because they want to emphasize it as a kite option and make it a bit more viable on other random champions, such as RFC TF (a la Froggen). However, even in this case, they should at least make the MS duration scale from 1 to 1.5 seconds by level 18. It currently has no late game fantasy and this may nudge it more to a kiting late game fantasy.
Right now, these problems aren't even that evident because the games are more or less decided before late game hits. Outside of preseason, Fleet Footwork would be even worse. I think all 3 keystones should be chosen for their niche and there shouldn't be a distinct scaling advantage for one or the other. They should just do different things well.
EDIT: The minion healing effect on Fleet Footwork offers another balance lever. Healing off minions can help laning quite a bit even at the 60% value. If they're worried about scaling buffs making it too oppressive early on, the healing from minions can be a lower or scaling value. This would open up additional power budget for late game.