There really is no need to have the ecryption... it would require a complete recode of the packet system in the core. Sure you can request it, but I dunno how many people will go to the trouble to do this. It seems more logical to use what is already there and use razor/uog to connect to a server.
Also the encryption doesn't supply any protection... it has a standard key which is not protected in the client. Plus everytime the key is changed, the packet code would have to be updated (or be so bogged down with versatility that it would work with any custom key). It doesn't seem logical in any respect.
Also, if you support a myriad of clients, you would have to have multi-key support, which would make your server run alot slower. Not very many people like to be forced to update when they are on a 56K or AOL.