Not in this thread, no. If you'd read my post, you would have seen that. For your benefit, I will restate it here: the current "advertising" being presented to greek recruits includes a significant portion of them saying, "You can't get this social activity or that academic support in the residence halls, but you can get it here." It's stuff that is flat-out lies, but they continue to sell it because it helps them recruit. I have no idea if this has gone on for a long time, or has only started in recent years, but it doesn't matter. It's going on now, and I wanted to address it.
If you're talking leadership positions in those large events, then yes, the greek percentage is still quite high. There are two big reasons for that: (1) greek chapters "heavily encourage" (read: essentially force) members to get involved on campus. That is straight out of the mouths of a good number of my greek friends. (2) Homecoming is a greek-only event. Somewhere along the line, they decided that greek week wasn't enough attention-whoring for them, so they hijacked Homecoming and made it all about them. The greeks are now the only ones who care about homecoming, so it stands to reason that they are the only ones who apply for leadership/organizational positions. That is the reason you failed at getting residence hall students to join Homecoming committee: they don't want to help greeks plan how to celebrate their own awesomeness. Every year, homecoming committee is over 90% greek, if not higher. Dance Marathon is- unfortunately- starting to head down that road, as well.
If you're talking about the clubs and organizations on-campus, I strongly disagree. I'm involved in a quite a wide variety of activities around campus, and nearly all of them have correct proportions of res hall, greek, and off-campus students. A few of them have very high residence hall percentages. I can speak from extensive experience when I say that students in the residence halls are highly involved, even if it's not in the activities you want them in. There are many activities that are specific to residence hall students, just as greeks have their own little things- did you consider those?
In addition, most of the residence halls are large enough to be socially self-sustaining. For example, Friley Hall and Helser Hall house more people than the entire greek system. As a result, there are TONS of events and groups and informal social activity that happens just within those buildings.
Correct. Residence hall students do stuff out in the community a lot more than greek or off-campus students do, for some reason.