Hi! We chose to do this on purpose to reduce the file size of the ZIP file. While it wouldn't matter too much for the free version of the game, the paid version goes through Patreon. This is important because most people won't keep their subscription running, only paying once for it only to let it expire at the end of the month. Most people prefer to keep their ZIP file locally in case they are restricted from further access through Patreon, and then it would be convenient to have it compressed. As for the free version though, why it's done is mostly for convenience, to not have it differ too much from the paid version