The fact that coming out is still such a hard thing to do makes it a big deal. Non-chalantly shrugging off someone's coming out can undermine it and make it appear trivial, whereas it's an important realisation, communication of trust. It's like saying "I'm getting married" and getting a "who cares, why do you want to label yourself". It's important for people because it's a large transition. Sure, if the person doesn't want to make a big deal about it, just like if they didn't want a big deal about their wedding, it isn't required, but you shouldn't just ignore it.
It was a brave thing for him to do, and it will have an enormous positive impact on other people, and be one of the minute steps towards greater acceptance in society. The fact it made news means it's important to a lot of people, be it for positive or negative reasons. Not only does it create a possible role model, but helps highlight societies opinion, by either hearing the opinions of people around you or from the media.
There hopefully will be a day where it doesn't make news, but we're not even close to it yet.