I do understand your point. The satisfaction of being the most valuable player is unmatched. However, MVP decisions are very subjective in nature so standarizing them is not easy.
In games, you have people whose night actions are so on point, they’re the main reason for the win of their faction, even when the player was not so influential during the day phase. In the same line, you have players whose day phase performance is on point, however, their night actions are not so accurate.
It would be pretty much up to the host’s appreciation of each player’s performance and what they consider more valuable, to give the MVP title but that means the metrics will vary from game to game and not every player will be measured by the same unit.
That’s why I think an event every now and then, to give recognition to the most influential players, taking in consideration a pool of games, is a nice way to go about the MVP medal.