Being a dramatic monologue, this poem sounds exactly like what it is—a dude talking. He stumbles over his words, repeats himself, hashes things out as he goes, and even has hints of an accent or dialect, what with the way he says "'list" instead of "enlist." Plus there's that awesome use of the word "nipperkin," which probably sounds plumb strange to us modern-day Shmoopers, but to a turn-of-the-century Brit would be a normal, everyday kind of slang. Sure, the poem follows a strict rhyme and meter, but it does so without losing sight of what it really is—a spoken poem, with a chatty vibe.
What's conspicuous here is what we don't hear. There are no grand speeches about the glory of war, no philosophical ponderings about sacrifice and death. This guy is very much a dude using a dude's vocabulary to try and make sense of something that really makes no sense in the first place. The simple, straightforward language of the poem is yet another way Hardy emphasizes that fact.