One of the ways I've grown as programmer is by applying suggestions given to me in peer reviews. I've often learned more by feedback given in these reviews than any google or stackoverflow search could have taught.
Unless there is a misunderstanding of the intent of the code, most of the time, the suggestions should be taken to heart. The suggestions are made to help support future maintenance, make the code easier to understand, and almost always a general improvement to the final product. It is very, very rare for a suggestion to be made based purely on an arbitrary point of view made solely for the sake of commenting.
When suggestions are made for changes to my work, it provides me an opportunity to take a second look at my work and attempt to make the work better. Often times, these suggestions are usable in any future work I do. Now the reviewer doesn't need to continue to make the same suggestions with each review. This makes their job much easier - and mine to - because I no longer get