Every industry has aspects or branches that, at face value, seem small. Some people want to make it easier to take pretty photos, and I don't think there's anything wrong with that.
I think the argument is bunk. It takes tremendous capital to solve problems like "healthcare reform" (whatever that really is) and self driving cars. I've seen few investors willing to invest in "big ideas". So, instead, we see lots of Instagrams and Zyngas.
"I lack capital" is a very silly excuse given that the HN community are among the richest people in the world... by definition, if you have the luxury of even thinking about moving to Mountain View and starting some web site, you are among the richest people in the world. A lot of people wake up in the morning and their first task is to figure out how they are going to eat today.
There are plenty of people with big ideas, feature them, befriend them, help them get money. If you think something is important build it or help they people building it leverage it. The solution is never to make the people doing things you don't consider big feel small themselves.
Of course this is a mechanism that goes horribly wrong in some societies, but it's our job to make ours as good as we are able.
However, I'd say that trying to solve a hard problem, not photo sharing, has a higher likelihood of producing these improvements. Look at how competition in space, military, chips, etc. did this.