It hasn't been removed, but it's bugged in the 64-bit version of the game. If you switch to the 32-bit version it still works. (Not that's a really convenient way to do it, but it's there.)I remember that in the past in the armor shop of harbor it was possible to preview cosmetic armors.
I don't know why that feature has been removed and we don't have any way to see cosmetics on our toons: sometimes I can see them on the web but that discourages me from buying them if I don't see them on me.