Im not biting down on straws, when putting it into your mouth you aren't holding a straw with multiple fingers like a utensil and it can tap into teeth with the entire weight of the glass and drink behind it because it is not really secured well and it moves. A plastic or paper or silicon or even a bamboo straw its not such a problem because teeth are harder and dig into or bend the material. Glass and steel don't do that and are the equivalent of tapping a tooth with a tiny hammer.
Glass and steel straws sound nice on paper, but using them is a whole different ball game.
Straws are just another utensil, I agree with OP that we could largely make do with alternate materials for them.