Mainly because ALL researches count towards the rising costs. Nobody who is aware of this mechanic is going to research the drones or advanced grenades. Maybe not even grenades at all. Anything that is optional and only makes your life a little easier will be skipped. I'm sure that's not what you intended, but that's how it will go for anyone that realizes what is going on. It will punish anyone who doesn't notice!
I'm never going to research the Text Plates due to this. Nanobots? Maybe a little. Land Mines? Absolutely not.

If costs were based on what Age they're associated with, it would be a lot smoother and more reasonable. Earlier researches would stay cheap, and optional researches wouldn't increase costs of later ones.

This is mentioned in the InfoTron, under Age of Technology. I'm not saying that I agree or disagree with the decision, just that it should be easily available information to the player. I'm most of the way through the game (just unlocked the fusion science pack), researched most techs, and stuff only costs 2.5k each. Given the cost of end-game vanilla techs, and the approximate costs of other overhaul techs toward end game, this seems pretty on par.

Also, it can be disabled under the Mod Settings, to revert back to the vanilla costs.

I don't see any way to revert back to vanilla costs. All you can do is change the behavior of the scaling.

In my experience, this is a big issue very early on (during red and green science), because depending on the order of research, a given project can take 20 packs or 200 packs. However, later on you stop caring whether something takes 2000 packs or 2200 packs and you just research everything in a whatever order.