I find it interesting that Wordsworth appears so humble in the preface. The most fascinating part of the preface, for me, is this line.
Several of my Friends are anxious for the success of these Poems, from a belief, that, if the views with which they were composed were indeed realized, a class of Poetry would be produced, well adapted to interest mankind permanently... (see second link)
Wordsworth seems to be suggesting that this new type of poetry will alter the landscape permanently. Actually, he did, by not just writing the poems but also "defining his ideas of the primary laws of nature, the working of the imagination, the process of association of ideas, and the balance of passion and restraint in human conduct" (see first link).