The only thing that I get annoyed by is when I don’t get the hatches I would like–in this case Chingling and Mantyke to get the Pokedex entries–but you are coming across like a whiny brat. The game certainly isn’t perfect, but be grateful that every hatch you didn’t want gives you Stardust and Candy you can use later.
Take what you can get, use what you can get, and keep trying. They give you a one-use Incubator every day–which I’m grateful for since I can’t afford to buy too many incubators–and I have had some amazing hatches with what I have.
I haven’t hatched a Shiny from the 7 km eggs yet, and honestly, I don’t care. I’d rather hatch a Chingling and Mantyke before the event is over–and there’s still plenty of time–but even if that isn’t the case, those same Pokemon replaced their evolved forms in the normal egg pools as well, so it will still happen in time.
Patience is a virtue, and if you feel like you wasted your money, stop giving them money. The game plays the exact same with or without your money.