Again, there's a confusion between thought and senses here. Seeing is not thinking. Taking what people can see =/= taking their memories and thoughts. A memory is what you remember about an event. A thought is how you interpreted it. The sensory input if how your body catalogued a stimulus. There's a world of difference here. So again, I ask: criminals have their possessions confiscated if authorities believe they can be used as evidence to convict them of a crime (and there's reason to suggest they are guilty). They also have their fingerprints, AKA a record of their interactions with the world, taken so that they can be used against them. How is one record of their interaction with the world different from another?
EDIT: Because it's much harder to falsify memories than it is to falsify your accounts of what happened. Similarly, it is much, MUCH harder to make your senses lie than it is to make your tongue do so. On this same token, would you be opposed to lie-detecting spells? Unlike a polygraph, they don't have a chance of failure, so long as magical protections are dispelled and you phrase your questions carefully enough. They override free will, because they tell the person talking to you that you are lying to them, with no chance of failure. So, would you argue against them too?
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Twostuck, Homestuck RPG: http://www.gamefaqs.com/boards/8-gamefaqs-contests/63360266