As I've said in the other NIN thread, I play the 3 melee DPS, and I use all of them for different reasons going from personal taste to FC needs, if we need the high sustain dps I go MNK even with all the dancing, if we need burning and heavy hits I will go DGN, if there's no need of anything specific and I don't want to mind much about positionals and such I go NIN.
And that's what I like about the 3 melee, each has it's own way of being played, and I can use all of them depending on my mood.

Now, if SE turns NIN into a MNK with daggers, why the hell would I play NIN? for the looks?
Since I'll have to dance, then I'll just play MNK with the perks of not having to worry about mundras or goading WAR or other melees.