The real issue here isn't about need more space. But about a huge number of players who actually have and play alts. Yes one character could do it all but many of us like different looks race, sex and all that based on an ideal we have for a character. We should be able to send useful stuff including crafted goods from own main to our alt and so forth.

This has nothing to do with RMT. Its easy enough to code that you can mail to others on your own account. It wouldn't be that hard to make it so you can send friend requests to offline players. Its simply the Devs do not care about doing so and using a BS excuse as their reason as they have no valid excuse.