This is exactly what I was wondering. Why bother? Just for some minor patent issue?
It's really a matter of principle. Plenty of people care about openness, that's why we have free software and all that. The same applies here.
And yes it's minor as I've never had to touch the issue as an end user: it just works. Videos play, without me having to pay anyone anything.
Sure you have to pay someone. You just don't do it directly, you pay the hardware manufacturer, who, in turn, payed someone else.
On the one hand I am glad to see competition, different approaches to the same problem, let the best one win. More codecs, more attempts to find the perfect video compression, that's a good thing. However when it comes to standards, it's gettig trickier. How many standards to support? Which one is to be "the standard"? And with H264 as it is - for me as an end user completely free and doing the job well - I don't see much room for VP9, really.
It's not always the best that wins, but rather the one with the largest company backing it up, or the one with better marketing.