Congrats on many levels! Nicara=1.3 times Instagram but several magnitudes greater than Instagram, when it came to solving hard-technical problems. I know, it is a dubious comparison but I am biased towards entrepenuers/founders who solve hard-technical problems. I am pretty sure, someone will argue that Instagram was pushing the boundaries of sharing, and in some fuzzy/meta way improving the human condition and experience in non-tangible ways, and in the process will end-up solving hard-technical problems (scale, data-science blah-blah). Let us just say, I disagree. Expecting to be voted down to oblivion.
I can understand your disdain for Instagram's frivolity, but people said the same about Twitter and it ended up playing a major role in the Arab Spring, whereas almost no one outside the techworld knows or really cares who runs their infrastructure. Of course without this infrastructure it all wouldn't work.
Like you say, comparing the two is like comparing apples to oranges, you can't really argue one is fundamentally more important than the other.
Instagram is a pretty much a self-contained service (i'll draw no conclusions about the frivolity it enables, just wanted to draw a distinction between the two.)
I do agree that "infrastructure can only be as useful as the applications they support" but I disagree strongly that "there isn't much point if it is just for our own edification". Advances are built on top of each other and some of them can seem obscure to the lay person. If no-one were pushing those boundaries we might not be in a position to discuss whether 'facetagram' is more impactful than 'instabook'. In that way, I'd argue that infrastructure is fundamentally more important due to it's multiplier effect (consider what EC2 has enabled).
I believe Marc Andreessan once said that Netscape wouldn't have been possible were it not for all the technology/infrastructure that went before it. He likened it to the icing/frosting on the cake. I can't seem to find the exact quote now though.
I agree that we need both. It's just that we seem to get a lot of the first and not enough of the second.