Sheesh. This is a fairly low priority feature. I'd like it but I'd much rather have more important functionality than something that players can manually do themselves by checking stat priorities for existing sims and identifying items that can be safely discarded, like, e.g., much older lower ilvl pieces with non-optimal stat combinations.
Major patch has been released as well as GloNet and scripting all the new ToS bosses. I'm sure, like me, you can manually check the pieces you have. I'm a druid and keep multiple sets for four specs, so if I can do it, you can do it
TD;DR manually check & discard stuff if you need space or wait patiently until the devs have time.