There is also the symbolic value. It was a "coming of age" event to a certain degree. I believe go was the last classic board game that researchers had been longing to conquer.
I haven't looked deeply into this, but my understanding is that image recognition is still somewhat subpart outside of well-curated datasets. Is that not the case anymore?
The same holds for AlphaGo and Watson. Also, my understanding is that they are more technically interesting than Deep Blue. Given how recent these projects are, their legacy is only beginning to unfold.
I agree with you that applying this tech to domains other than games is no easy challenge. But I would be very surprised, in the long run, if events like this are not documented as key steps along the way at some point in the future.
1) Too much credit is given to Google for this result. What I see as already a huge brain drain on society is only going to get bigger.
2) People are going to expect that if "computers are smart enough to play Go", they're smart enough to do ____. What goes in the blank? Very little right now, but I guarantee you investors and the public have a lot of ideas and think it's around the corner.
Hopefully a lot of good things will come out of this wave of AI, but who knows what or when. I think the point is that there may be a panic and contraction before anything really awesome happens, and a lot of that is going to be because of "stunts" (for lack of a better word) like this being overhyped.