I'll explain what the problem is. You're looking at DLC from a player's point of view. I will explain to you my truth, my vision as a developer.
I really love and respect my team, because we make a quality product. After conferring with the team, we decided to release this DLC anyway, and installed it for a small amount of $2.49. I want to note that this DLC has already been shown to players, and there was even an opportunity to download it for free (whoever had time, downloaded it last year).
Our bonus is the main game, which the player can download for free or pay for a new version.
You're comparing an indie developer to big projects, but buddy, we're not Cyberpunk 2077, which releases an update for free. But Cyberpunk 2077 doesn't offer such low prices for a $5 game either. In addition, it’s not for me to explain to you that the 18+ market is just starting to grow, a couple of years ago it didn’t exist at all (it was Underground).
Trust me, I love free cheese too. But if you are not ready to pay for it, then just wait until it is free, or pass by. After all, this addition will probably also acquire bones and meat in the future, and it will become larger. Paying 1 time you get it forever.