There were other interesting things about this author reading than just the audience. (One was the shockingly high price of textbooks, but that's not relevant right now.) The most important one is that it confirmed in my mind that written fiction is meant to be read to oneself and not heard by someone reading aloud. This has nothing to do with the goodness or badness of the piece that Bear read from. What I'm talking about is the way we internally pronounce things as we read, the way our internal cadence and rhythm develops, the voices and accents that we assign to characters. You know, all the stuff that we do to fill in the blanks and really enmesh ourselves in the fiction. This cannot come across during a reading unless the author is also an excellent actor.
This brings me to the next point. A reading, to me, seems to depend on a reader's performance capabilities and less on their ability to write well. You've heard it said that the best actor can make the worst dreck ever written sound good. That's probably true in every case except Eragon. The thing is, reading out loud tends to pull someone involuntarily into performing the piece instead of just reading it. That seems to distract from everything. It distracts from the author's written work, which is visual in nature and we cannot see the paragraph breaks and interrupted dialogue and other clues that writers give to readers so that they can understand better. It also distracts from my internalizing the piece and living vicariously through the protagonist because I'm more intent on watching the reader than reading it myself.
All this leads me to believe that there must be another purpose beyond the enjoyment of fiction that lurks behind author events and readings. Not that they are bad, because I had fun and enjoyed it, but they just must have a different reason for being.