In Writer, the point in the text where a comment is pointing to, is treated like an invisible character during keyboard navigation. Also the comment can be deleted like a character. That is wrong behavior, the comments should be transparent for the purposes of the text editing.
I'm afraid that if we change that, then a few minutes later a regression bug will be filed, saying that pressing "del" in front of a comment anchor point no longer deletes the comment.
So - feature not bug for now (?) - unless the UX team want to get deeply involved.