Hello there, have been playing MMO's for maybe about 12 years now!

Hiding peoples glams is not a supportable idea at all.
If you do not like looking at other people in video games, I think what you are better suited for is called solo gaming!
When it is a "MMORPG" this means that you will see other players! This idea sounds like that a thing which you do not like.
Therefore, I think this is a situation of perhaps mistaken genre.
In 12 years of playing MMO's not one has ever had this option and it is best to stay that way.
Even if "well they cannot SEE that I turned them into NPCS!", it is still a bad idea.
If you can disable their costumes, you are disabling a part of their personalities and this will make it much easier to not understand them and then probably react to things a little harsher than you would if you knew they were in a frog suit, actually.

MMORPG's are entirely about socializing and if everyone must fit your world then I think you may not be ready to socialize yet.
Also!

Why are you looking at what your tank is wearing during a fight?
I think you should focus on the fight and work together to clear instead of zooming the camera in on your teammates.
If you have time to zoom before the fight, you also have time to say hello to everyone and explain to any first timers should they say that they're nervous, instead.