How about alien data slates?
I meant more something like, why would it be sequential? I can imagine it would work if there was a specific branch with "tiers", which can only be discovered if you know the previous step. It's a valid idea, but would require planning for it in advance, so it's hard to just shoehorn it into an existing mod. With time, maybe.
My thinking was that as a player, knowing that the sequential system is used, you can determine which free techs you can't easily get by other means, then hold off on researching the parent tech until you've crossed off the ones before that.
Yes, but it's only a valid concern if you can do that as a player. Nobody said these researches can be found anywhere else at all. It's a modder's decision.