Firstly, it's not just for the mount, it's also for the streamed panels at blizzcon.
Secondly, if $39.99 is a month's wage then why in the hell are you spending a month's wage on video games or more than 1/3rd of a month's wage on a WoW sub? Also, how the fuck is someone going to view the blizzcon stream from some 3rd world country where $39.99 is a months wage?