The Sidebar in writer has the tab Manage changes where you see the changes. As Comments are also some kind of Review Information, please add the Comments also in the sidebar.
The idea was discussed a couple of times, e.g. in bug 101714, but apparently never filed as an extra ticket.
Heiko has already suggested that comments go into the revised Navigator (103030), and comparing the conversion of a dialog into a sidebar deck is completely different from comparing always visible items in a document and putting them in a deck.