The arguments for Bitcoin are the same arguments for cash with respect to censorship resistance. The gist of it being that sometimes the law and what is legitimate diverges to a point where there are legitimate value transfers that are outlawed. It is only by having a way to do these legitimate value transfers that these things will ever be revealed. So in a sense, it keeps the law "in check".

See the comment here https://news.ycombinator.com/item?id=14572940 for a more eloquent explanation. From the link: "The individual ability to buy anything, much like the individual ability to read anything, is both an important personal freedom and an engine for social progress specifically in the areas where society's mores are wrong."