Mudra why so many ninja don't use them?

[Gemina]

The mudras require more memorization than most jobs to remember which combination does what, and in which order you want to use them optimally. It's also rather unforgiving if you fat-finger the wrong combination, although at least nobody's likely to notice the rabbit on your head, since as a melee job you'll be buried under everyone else's flashy effects anyway. On top of that, ninja's old niche of aggro manipulation no longer exists.

It becomes muscle memory just like anything else after a time. For standard ninjitsu, all that matters is the last input, the previous input(s) can come in any order. Only where TCJ is concerned does the order of mudra matter, and like I pointed out in my last post, TCJ is an abomination of a skill that should never again see the light of day.