I think the straightforward truth is that literary criticism has value for the same reason video games or DnD or whatever have value: people enjoy them and that's enough. I don't buy the argument that lit crit is really vitally important for making the world a better place (except insofar as people want to do lit crit, so them getting to do it makes their lives better) or solving political problems or whatever.
Yes, you can complain that society spending its resources on lit crit is therefore immoral, because there are hungry people to feed instead. But of course if you were going to make this argument you would also have to complain about the immorality of spending our societal resources on video games and so on, which STEM nerd lit crit dislikers rarely seem to do, otherwise I think you're being hypocritical.
For my part I think that probably convincing people to give up all their worldly pleasures to help the poor is not feasible, and in light of that it's cool that lit crit and video games and so on exist, because people like those things. And ideally enough progress can be made in uplifting the poor (either within or without our current economic system) that these kinds of trade-offs become a memory of the distant past, and I'll be able to endorse frivolous public funding of the humanities or million dollar blockbuster video games or whatever with no caveats. Because I'm not that worried about optimization, and as long as all the mouths are fed I don't care so much about society "wasting money" on fun.
At present I can probably only endorse these things provisionally and selfishly: first off I like video games, and I like reading media analysis, so I'm glad they exist. And second off, it's not like the money that goes to humanities departments would be going to feed the global poor anyway, it would be going somewhere else which I'd naively wager would be either equally frivolous in this narrow sense (pure math, econ, paleontology) or actively harmful (weapons development). Maybe not, who knows. Anyway I'm not terribly aggrieved that it's going to the humanities instead. If the alternative really was feeding starving people I would support that in a heartbeat, but it isn't.
And, as I said, hopefully in the socialist future we'll be able to waste all the money on humanities and non-essential sciences and cool video games that we want. One can dream.