A voluntary sharing of thoughts would
be like a new Internet. Quick communication, but with lots of wrong information being spread. Accidentally acquiring other people's prejudices would be like catching a computer virus . . . one that you may never be able to purge.
However, forcing (or even volunatry) communication of everyone on the planet simultaneously sounds like the ultimate Mind Rape
Imagine every mean, petty and cruel thing you've ever done in your life. Imagine every mean, petty and cruel thing that other people you know have done. Multiple this by several billion.
Everything you hate: murder, rape, torture. You not only experience it from the victim's perspective, you share the perpetrator's belief that their actions were justified.
Every belief in the world is now jammed together in a contradictory, jumbled mess. You are simultaneously an atheist, a Christian, a Muslim, a Buddhist, a neo-pagan . . . and thousands more. You hold every political view. All bigoted, hateful and prejudice thoughts on the planet are now your own.
All is chaos. Death is the only escape.