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.

I think the main problem of this is, that it encourages leaving some techs not researched at all
My proposed solution to this: Make tech of each stage only affect cost of techs in the same stage, and infinite tech costs are not affected by anything
However this may be very difficult to implement, as Factorio doesn't allow changing tech cost on the fly, and this mod does it by changing the tech cost modifier instead of the base cost
It should still be possible to isolate the infinite techs from the cost scaling though

At the risk of sticking my head above the parapet, increasing research costs was one of the things I most enjoyed about this mod. It meant that what to research and when became a trade-off that required some actual thinking, and each age needed at least some kind of plan as to what technologies would be needed so as to not get death-spiralled. It also played really well into the "new better recipes" mechanic: do you go for a technology that offers nothing strictly new but helps produce the resources you'll need, or do you unlock one of the new toys that became available?

Another thing is that you can't really predict what one person's "killer technology" is going to be: I, for one, love landmines and poison grenades, they're great at dealing with nests, and in Vanilla they come along right as your starting resources are running out and you're thinking about expanding. Scaling research costs means I can beeline the poison grenades and be happy, whilst someone who doesn't like them can beeline silicon wafers and be happy. In effect, everyone gets to cherry-pick the stuff they really want at a discount. The quota of technologies to unlock the next age smooths out the bumps a lot, it's not possible to get your tech tree too unbalanced because you still have to research most of the available technologies to unlock the next set.

That you can stop caring about research costs as the game progresses is actually good, and it fits thematically with the mod's premise of showing you scarcity (coal belts, steam pipes, power generation, mining, etc.), then freeing you from entire mechanics and seeing how you adapt.

I would be sad if technology costs were reverted back to vanilla, I think the price going up adds a lot to the game.

The research costs scaling is what drew me to this mod, seemed innovative.

I like the idea of the cost scaling and the age mechanic, but the issue that I've found is the way the two interact. The moment you hit the threshold for the next age, you research that age immediately and then proceed to only research techs from the new age. The fact that techs from prior ages contribute to the cost scaling but NOT the age progression means you're incentivised to NEVER return to the techs from prior ages.

A similar but distinct problem is from various technologies added by other mods in the modpack or extra mods one chose to add, which also contribute to tech scaling, but don't contribute to ANY age progression, meaning there's no point in the game's progression where it makes sense to research things like Text Plates, Nanobots, the Spiderling, or the solar tower unless you REALLY want them.

The main saving grace is that scaling tech costs have a hard maximum for a given setting, defaulting to 2000, which, while I haven't gotten to the endgame sciences to know how expensive they really are, doesn't seem that bad all things considered. Experimenting in a test world also seems to indicate that infinite researches don't contribute to the scaling, though they might be affected by the scaling.