That is why: it is only good. Not great or spectacular or stunning. It is a step above many yaoi manga, yes, but is not brilliant. 5 star ratings should be used sparingly, sparingly. Imo, a 5 star manga needs to be more than cute and adorable (though this certainly was)
omg why is this a 4 star? it's so good!! i love every story. it was soooooo good. so cute. so adorable. i love it!