I meant that in a normal survivors-like, what upgrades are available to you are randomized when you level up, and in this game they're instead determined by what color lights you've picked up. However, what color light is dropped by enemies is still random, thus upgrades are still randomized, just when they get randomized is moved from "when player levels up" to "when enemy dies".
It's not technically the same since you could avoid picking up colors of light you don't want in your upgrade pool, but it is both difficult to pick up XP you want while avoiding XP you don't and also detrimental, since upgrading quicker is just better than cherry-picking upgrades.
I'd thought it'd be cool if there was a way to better specify what color light gets dropped by enemies, but thinking about it now, I can't really come up with a way that wouldn't be more clunky than it's worth (such as them changing color over time, interacting with your center crystal sets what color is dropped, or color getting determined by the enemy's distance from player upon death). Additionally, a big draw for games like this is choosing from options you wouldn't normally pick, forcing you out of your comfort build and adapting into something new.
I hope this overly verbose way of saying "ignore me, I don't know what I'm talking about" was at least insightful, if probably not helpful, and good luck with the project!