Because Gendo is the Uberpimp. As some might say, "Oh, Daddy!" (This is of course ironic in the face of Gendo's obvious Daddy issues, due to which he constantly seeks Futchan's approval.)
Alternatively, it is quite possible that Asuka forced them into it, saying something like: "If
I have to wear that perverted outfit, and freeze, the Commander should set an example for us, and show solidarity. If he doesn't do it, I'll pop his head like a Bishounen." (Her words carried a bit of extra weight, as she was at the time inside of her mother, and the umbilical cable was not plugged in. The Commander and the one under him (
ohohohoho) had no choice but to comply, lest they face the red wrath.)
(Also, hi Ray!
)