It is pretty highly rated, honestly. Some people view yuri negatively and many only accept "likeable" MCs. 7.7 is pretty acclaimed, considering that.I don't know why this has an under 8 rating, cause this is a damn good manga.
Maybe it's cause with this premise and the 'suggestive' tag people were expecting something horny and were disappointed? lol (it's actually a very funny and somewhat wholesome story!)