I recently finished a collection of short pieces by Neal Stephenson, who is maybe my favorite living author. (The other possible candidate, Iain M. Banks, recently died.)
Stephenson's Some Remarks includes a piece, "Why I Am a Bad Correspondent," which explains why he is unlikely to answer an email from a stranger or accept a speaking engagement (he needs to be able to concentrate his time and attention on writing novels.)
While is isn't really germane to the main point of the essays, the article includes this passage:
Likewise, a novel represents years of hard work distilled into a few hundred pages, with all (or at least most) of the bad ideas cut out and thrown away, and the good ones polished and refined as much as possible. Interacting with an author in person is nothing like reading his novels. Just about everyone who gets an opportunity to meet with an author in person ends up feeling mildly let done, and in some cases, grievously disappointed.
Most of my encounters with authors, whether in person at a science fiction convention or sitting in an audience at a speaking engagement, have been pretty pleasant. I particularly enjoyed meeting Robert Shea many years ago at a worldcon in Boston; he was very nice and answered all of my questions. I did think that Jo Walton lacked charm and didn't seem particularly interested in being nice to her readers. (At a convention, I showed up for a "meet the author" event that was limited to a small group of people sitting around a table. Walton announced that there wasn't room, inviting me to leave. Another person said he was just leaving and got up, so I got to stay. Wouldn't a normal author, or a normal person, say "Pull up a chair, there's plenty of room?").
But I think I probably agree with what I take to be Stephenson's main point: In most cases, listening to an author talk is not as interesting as reading their best books. I think Robert Anton Wilson may be a possible exception, at least on his good days, as his interviews are often very interesting. But in most cases, I've formed my opinion of authors by reading their books, not by listening to what they had to say at science fiction conventions or speaking appearances.
(I never met RAW. He occasionally went to SF conventions but wasn't the kind of guy who turned up at worldcon every year.)