[Erlich_Bachman]

Being careful is always good, but the dangers are overestimated and the benefits underestimated, by most people.

In terms of security, you could solve 80% of problems you mention by a hardware onoff switch, which would cost next to nothing. A large part of rest of the problems could be solved by limiting the information flow into a certain format/context: imagine just a 4K screen inside your mind that you can look at if you wish, but you always know that information comes from that screen and not from somewhere else. Even just such a dumb usage would be tremendous upgrade to humans everywhere. How do we know it won't give you any "thoughts"? Just limit the information flow to pixels. The interface won't even know what information you look at your internal screen, the most mischievous thing it will be able to do is to maybe make things black-and-white, or make something flicker in an annoying manner.