Understatement is a figure of speech that describes a situation as less important or serious than it really is. It is often used to be more polite, or for ironic or humorous effects.
The passage uses this figure of speech because the speaker is deliberately trying to convey that his desire for someone to do something is not strong, however, in reality, the repetition and the emphasis they put on these ideas are proof that the speaker does care, and would like the other person to do what he says he does not want to.
