I've admittedly only leveled MNK to 80 then set it aside, but I only remember Back and Flank positional requirements which, if you're close to the transition area, 1.5 seconds is more than enough to move between. Also, even a MNK not hitting positionals or hitting positionals sporadically would do good DPS. The fact that there are so many positionals give them a higher skill ceiling which is great for players that are looking for a complex melee class.
Also, the MNK rotation may be a little complex, but it was fairly easy to get into a rhythm with the positionals and it _feels good_. You brought up Dragoon and that has something that I would like to see with MNK though. MNK has very little visual indicators on whether or not you're actually hitting positionals (bigger numbers, if you know what the numbers should be). Whereas Dragoon has 1 ability that I'd love to see at least on MNK; Raiden Thrust. It replaces the combo starter with a slightly higher potency ability if you hit your positionals. It'd be great to see something like that because it's a nice visual indicator that pops up and says "Good job!" Having Dragon Kick replacing Bootshine with another ability if you hit the positional would be more interesting than the current Leaden Fist (double Bootshine potency) at the very least.
Maybe it's just me though