I can speculate, but there's no particular reason to think I know the "true" reason.
My ability to logically defend my preferences is not strongly related to their importance to me. So if I particularly like or am emotionally affected by some piece or genre of music and someone notices me listening to it and argues with me or explains why I am wrong to like it, I may find that when I listen to it later I only feel wrong and cannot enjoy it anymore.
If I am reading material that is not interesting enough, I may be judged unintelligent as a result. If I am reading material that is interesting enough, I may be expected or demanded to produce insightful commentary, and when I fail (which I will---if you put me on the spot you're lucky to get audible words out of me let alone anything sensible) I may be judged both unintelligent and unaware of it since I was obviously reading material beyond my comprehension and couldn't even tell that this was so.
My value system is under construction and not especially stable, and if my reading material is relevant to this I risk failing to defend my values and being forced to admit the superiority of the value system of whoever happened to catch me reading. I don't want to end up in the position of, say, admitting that utilitarianism is superior and, since you're whinier, you obviously care more about X than I do and therefore I must go along with your position on X. (Sounds like a strawman, but nope. I've actually been argued into that one before. I seem to have a particularly weak will.) Therefore I try to avoid anything that might lead to discussions relating to my value system. However if I only hide my reading when it's related to my value system, that's practically telling you when to harass me, so I have to hide all my reading in order not to give away that information.
In a telepathic society I would feel required to restrict my thoughts to ones I could defend in an argument, which in practice means I could not get away with developing any new thoughts unless they spring into place fully formed.
That all makes sense. However, in an ideal telepathic society, people would learn about those who need time to think and space to appreciate what you like, and you'd be cut slack and not be argued with about things that aren't urgent.
For that matter, people who like to argue would always have someone available to argue with.
I asked this question on IRC before and got some surprising answers.
Suppose, for the sake of argument, you get cryo-preserved and eventually wake up as an upload. Maybe meat->sim transfer ends up being much easier than sim->meat or meat->meat, or something. Further suppose that you are not particularly averse to a digital-only existence, at least not enough to specifically prohibit reviving you if this is the only option. Yet further suppose that sim-you is identical to meat-you for all purposes that meat-you cared about (including all your hidden desires and character faults). Let's also preemptively assume that any other attempts to fight this hypothetical have been satisfactorily resolved, just to get this out of the way.
Now, in the "real world", or at least in the simulation level we are at, there is no evidence that telepathy of any kind exists or is even possible. However, in the sim-world there is no technological reason it cannot be implemented in some way, for just thoughts, or just feelings, or both. There is a lot to be said for having this kind of connection between people (or sims). It gets rid of or marginalizes deception, status games, mis-communication-based biases and fallacies. On the other hand, your privacy disappears completely and so do any advantages over others the meat-you might want to retain in the digital world. And what you perceive as your faults are out there for everyone to see and feel.
As a new upload, you are informed that many "people" decided to get integrated into the telepathic society and appear to be happy about it, with few, if any, defections. There is also the group of those who opted out, and it looks basically like your "normal" mundane human society. There is only a limited and strictly monitored interaction between the two worlds to prevent exploitation/manipulation.
Would you choose to get fully integrated or stay as human-like as possible? Feel free to suggest any other alternative (suicide, start a partially integrated society, etc.).
P.S. This topic has been rather extensively covered in science fiction, but I could not find a quality online discussion anywhere.