Core concept is that all information on the internet should be treated the same way by ISPs. Much like the principles of freedom of speech or press, it has both positives and negatives.
As a downside, it keeps ISPs from cracking down on, for instance, sites that host viruses. But it also ensures that corporations and governments cannot determine what information is spread among internet users.
Given that the internet hosts the closest thing we have left to good sources of news, I consider that an absolutely vital principle to protect.