There are quite a few hacker events with more of a flat-hierarchy, open-to-all-comers ethos, but yeah, you probably won't find them attached to these more high-profile media events (there are exclusive sponsored after-parties associated with events like WWDC and GDC as well, to add more examples). There's fortunately the whole other parallel world of stuff like Noisebridge, DevHouse, etc...
There are certainly plenty of exclusive events hosted by third parties at WWDC, but as far as I know, all of the official Apple events are open to all attendees, as well as (I believe) all employees who are able to attend the conference.
