I'm an introvert. Ask anyone. I can glad-hand with the best of them when the situation calls for it, but my nature is very introverted. Given that, and the fact that I seem to want to talk to everyone from the 7-11 guy to my apartment manager about the contents of my book, I think I see why publishers keep authors at arms-length.
We want to talk about our books, not about publishing them, or making money, or sales or schedules. We want to talk about what we were thinking when we wrote this bit, and why we made this tiny change last night, and the inspiration that gave us that other paragraph. If someone like me finds themselves wanting to talk to complete strangers about a book I'm writing, I'm pretty sure that the effect on a normally socialized human would be even more profound.
This may explain why so few publishers list their phone numbers on their websites.
Just a thought,