Are you aware of the psychological aspect of how bettors choose between over or under? For starters, over/under bets is a type of sports betting where bettors try to predict whether a combined number of score of both teams is over or under a predetermined value. It is observed that beginners tend to bet on the over side. Why? Because over means excitement.
I think people bet more on over than under, this is understandable because, like you said, over means excitement and shows that the teams delivered on what they are expected to do at optimal capacity. In my mind, whenever I play under, I see it as taking risk because in most of the leagues I bet, it is easier to get over than under. In football for instance, it is very easy to get over 1.5 which will be a winner the moment both teams scores or either of the sides scores two goals. It could vary for other options like corners, cards, and others.