I completely agree, Wardrobe is something a FTP player should have access too. 1mirg pointed out the main issues as to why it should be, one of the biggest being that it deters FTP player from buying costumes due to space limitations. What if i'm down for spending £5-10 a month on actual items be it costumes or consumables but just not premium membership? Well if inventory is an issue then I certainly wouldn't want to buy costumes.
There's an easy solution for this if NCSoft still wants to rake a few bucks out of people. Just put wardrobe access on the NC and Hongmoon coin store so FTP and paying customers can buy it. Everyone that has bought premium up till now will automatically have wardrobe access and new people can just buy it, pricing up to NCSoft ofcourse.
If Premium members are salty about 'losing' a premium feature then just compensate with another benefit. I'm sure NCsoft have plenty of possible benefits written down, Discount windstride prices, bigger daily quest cap, Higher transmute success chance, etc.