Am I responsible for a Wikipedia article if I wrote it?
If you think the additions are useful, consider adding them. You thought your time well spent building the pages in the first place, so I would think you probably have some interest in improving them.
If the changes seem to you marginal, or time consuming, write a polite letter to the proposer reminding them that you don't own the page so they are free to improve it. If you're polite and appreciative you probably won't cause offense.