Kind of need to understand the mechanism by which reading improves memory and reading capability to provide an informed answer. Based on assumption alone, I don’t think visual novels would have as great of an impact as reading books, especially on memory.

Visual novels take away some of the need to form memories from the text. When a character is in a scene, the image of the character is generally shown; the brain doesn’t need to recall a memory of which character it is and how the reader previously interpreted their description. And, related to descriptions, visual novels don’t need to give detailed character descriptions because there is (or will be) an image. The reader’s cognitive abilities aren’t flexed nearly as much as if they have to form an image from the text themselves.

Books that give insight as to how the everyman lives are not worthless and boring by default.

As others have said criticism is not hate. Also, if the person critiquing says they don’t like a genre and discusses that, it shouldn’t be a problem. However, if a person who thinks Dan Brown is high art writes a diatribe about how is bad and the writing is too descriptive and the book could have been 1/3 of the size and more fun to read. Then they deserve any reasonable feedback they get.

*reasonable - non-abusive and no death threats.