Quality takes time, I can't whip my artists to come up with an update every month, it's not possible and that's not how it works.
There are thousands of games to discover between each update, use them to expand your horizons or why not try to create a game yourself, so you'll see that not everything is done as fast as you think.
As for the skins to sell, there is no obligation, it is a bonus that had access to those who support the game every month, there is no obligation to buy it, it is only for the pleasure of the eyes