Ah just a formula that's always going to work, to make a fun, enjoyable experience. I like that it's not just one big upgrade menu but that it gives you a reduced set of options each level so you're making more interesting choices when upgrading.
I wish there wasn't a maximum to how much I can upgrade things. I wanted to keep going and don't know why the game didn't allow me to keep upgrading my cookie. I feel like these kinds of games stop being fun once you have finished upgrading things and have reached a maximum.