So you're admitting that you don't know as much about MNK as you implied earlier then.
Nope. Don't go putting words in my mouth.

As far as GL, losing GL isn't as punishing as you would honestly think. It takes roughly 15-20 seconds (less if you have PB, but PB isn't always ideal just to get GL3 stacks) to build up stacks again once you lose it (Roughly the same CD as Ninjutsu)...
It actually really is. In a game like this where your damage is measured on a per-second basis, 15-20 seconds of being gimped is huge and it *will* add up.

While I am not one to say one job is "harder" than the other.. However to play a NIN well and use their utility in the right moment, takes more skill then spamming 2x sets of 6 skills on a MNK.
The mere facts that NIN doesn't have to bother with positionals or a crucial buff that requires near-constant enemy contact to maintain make it a far easier job to play. There is absolutely no contest there.

The only remotely complex thing is memorizing what mudras do what, and ultimately that's really not much different than memorizing any other DPS' rotations or when to use each weaponskill.