Well, without Carmine's "Happiness Mc", that iconic moment won't happen.
"Really? Really really?"
CC and Mirall winning isn't really a surprise, CC really had a impact to the players who played Null first or latter, the Null is really far from the main story which lead to CC being the main focus instead of Mirall or the other girls. It's literally CC x Player, of course they'll like it.
Mirall being the whole reason of the Happiness series and her being a original character without basing to a real person carried it. Mirall is Mirrall, that's all I can say, her daughterly love is probably adored by the people.
P.S - I like how you add Hassan in the Heroine voting.