Actually, when you are writing for a niche market like suspense or romance, the readers are far more open minded and less critical than someone who reads Hemingway for enjoyment. Literary readers, and genre readers cater to two completely different audiences. I've noticed that readers of literary material tend to be a bit more pretentious (for lack of better word -- sorry) and willing to dole out a 2 or a 1 to a writer like Dostoevesky lol whereas a romance fan (For example) will write "Omg, I love it!" because the story moved or tittilated them in a different more simplistic way. I know this because I am an avid reader of genre books like Romance, and often find myself giving a 4 star rating to a book where I might have hated the characters or thought they were stupid. Why? Because despite its character flaws, the book may have held my interest.
You also assume too much of what writers value. I don't mind a 4 star rating. I don't mind a 3. I don't mind a bit of criticism. I would feel so foolish if I'd written a subpar novel and people had scored high. In fact, I would feel betrayed and patronized. I value and appreciate the truth.
I see no reason to go out and solicit 5 star reviews from strangers or friends for that matter. I am often very surprised when I get a review in the first place.