Because it's relevant to democratic discourse. Freedom of information is important precisely because it allows us to better understand the forces that shape our world, one of which is religion.

There has been a trend -I'm sure you are aware- of religiously inspired attacks, occurring across the globe. People who seek to understand this phenomenon require open access to information. This trend is important enough that it was a large causal factor in the 2003 invasion of Iraq, and, probably, a causal factor in the rising popularity of Trump. I take no position on either of these issues, but just raise them to note their connection to the issue of Islamic violence. It is important to democracy to be able to talk freely about things. (It is an unfortunate thing that some avenues of discussion are being cut off by media information suppression, and others are being cut off by the false accusations of "Islamophobia"; it is the perverted nature of this stifled discourse that allows demagogues to rise to power).

Some people would like to deny the relationship between Islam and violence. They have the right to do so, by way of argument, not by way of suppression of information. Clear heads are supposed to prevail based on the strength of their position, not their ability to hide facts that are contrary to their position.