Actually, when this poem was first published, it didn't even have a title—just a number. It was called LXII, which let readers know that it was number 62 in Housman's book of poems A Shropshire Lad. There were only 63 poems in the book, so this one was second-to-last. This is also one of only two poems where "The Shropshire Lad" is given his actual name, which is Terence. The whole book of poems doesn't exactly tell a story like a novel would, but it's organized around the character of Terence, as well as the memory of Shropshire, a rural part of England.
As this particular poem got more popular, people started reading and publishing it by itself, which called for a different title. In cases like this, it's pretty common to use the first line as a title, and that's just what happened here. LXII became "Terence, this is stupid stuff."
It's kind of cool to think about how this changes the experience of reading this poem. Making the first line the title makes it doubly important—basically you read it twice, so those words are really stuck in your head. And what is that line's central idea? Well, it gives us the opposing viewpoint, the argument against which Terrence will be making his case for poetry. It lets us know the opposing perspective from the jump, and the turn to Terrence's pro-poetry argument at the end is all the more effective.