It's a balancing act. They shouldn't be so big that they overwhelm or are the key features of the game, and they shouldnt be so small that they are inconsequential.
Sure. But it sounds like right now you're erring towards "inconsequential" by a fairly wide margin.
In my opinion, random techs should matter, but they shouldn't overwhelm features like faction traits (if your random techs matter more than the faction you selected then that's giving them to much weight).
Is it not possible to make techs be both random and faction-linked?
It also shouldn't matter more than your starting location.
Why not? Neither is more random than the other. Starting location is inherently mitigable, because you can travel around and build additional cities in other places.
They are not intended to be game changing.
If they don't change the game at all, then why even have them? It seems to me like you're passing over a significant opportunity to make the game more fun, on many playthroughs, and instead reducing it to a gimmick that effects next to nothing.
we wouldn't, for example, want players to get used to simply looking at their starting tree for random techs they got and always rushing for them because thats the most effective way to play.
Certainly, they shouldn't be powerful to the extent that static technologies are unimportant. That doesn't mean they should be limited to boring things. Pure numerical bonuses are not very compelling to a substantial portion of people.
ps. When we talk about big crazy game changing things, that's another piece of the design pie, that aspect belongs to quests.
Quests should certainly be important. I look forward to seeing what you'll be doing with them.