You quoted text which says that mIRC is a p2p application - why should mIRC have its file sharing system implemented in the same way as those applications when mIRC isn't one?
DCC works fine for me, and for thousands of others who use it. DCC is a very simple protocol, and Khaled is not the one who designs it. It only starts to break when you complicate things with stuff like NAT/UPnP or using it in a way it shouldn't be used (e.g. massive download sizes, a large number of DCCs).
As a note, UPnP support has been suggested on numerous occasions, using the Search feature will reveal many of those threads
Regards,
