Chris Kinsman, who was my track chair at VSLive! a couple of years ago, describes the speaker room situation at TechEd this year. Having given a few talks at these types of conferences before, I can relate to the situation. As a speaker, you want to meet people and talk to them about the conference. But you also need to have a quiet place to work on fine tuning your presentation, double checking your demos, or sometimes just checking in at the office while you're out. Even with wireless at nearly every industry event these days, the speaker room often has better connectivity and access to power strips, and some peace and quiet. Those things can be hard to find at most conferences. If conferences would do a better job at providing this kind of infrastructure, then the speaker/attendee interactions would likely improve.
If you attend a conference like TechEd and want to meet a speaker there, I advise you to e-mail them in advance to try to find a way to connect with them. Most people are willing to meet at some point during the conference and get feedback on the event or even on their presentation. Also, remember that many of the smartest and most interesting people at the event are attendees, BOF presenters, or other guests. Reach out to those folks if you can.