There are multiple hooks for removing the Tadpole, but they lead to nothing every time. Of course for the rest of the story to work, it can't solve the problem, but it feels very forced and frustrating that it doesn't give you anything for sacrificing both eyes, following leads to different sidequests, etc. It doesn't advance the plot at all and as such I consider it bad storytelling. In DnD terms, it's railroading.
You just expected to be in finish, when you reached first check point ...
Yes, it appeared like finish like and for our characters its important to look like finish, so they try to reach it ... sometimes its just check point, sometimes its just dead-end ... but your are still moving forward, and as you were allready told, you are still learning something new.
I also dont think that you can sacrifice both eyes, i was unable to try any healing metod involving loosing an eye with Wyll since he allready lost one.
And if we put aside that, if your character loose and eye and then decide to sacrifice other one ... well, i gues hes not fast learner. :-/
If for example you could cure companions, but not yourself for some story reason, this would lead to interesting character interactions and inject more background info. Would they stick around? If so, why? If not, will you meet again?
Cant imagine how would you uphold that ... like in that pool was all regular tadpoles and single one that was alterned with dark magic ... and that alterned one was conveniently not eaten by others, and even more conveniently implanted just to your character? :-/ I dont like that, kinda too much coincidences at once.
To be completely honest i dont even like the fact that you can undergo all "healing metods" with your companions ...
So they take all the risks. :-/ I admit that once i forced Lae'zel (when i didnt use her regulary) like this to be the one who will allow the Hag to remove her eyeball in order to "try to help" ... pretty stupid that you are allowed to do that, since Lae'zel is keep repeating to you that nothing except purification will work.
So if there is anything that could improve the story, its to remove option to undergo atempts to remove the tadpole for all your selfish, distrusting, or sceptical companions.
This cuts deep however: Because the main plot at this point is to find a way to remove the Tadpole and every attempt being foiled, I as a player have no reason to believe the next hook would be any different. Why would I follow the main plot at this point? I can see that the game is going for desperately grasping for any solution, but then there should be a justifiable belief that it's possible and more importantly a progression that tells us more about the problem. There was a tiny glimmer of that in the Hag solution, but not enough to get me invested.
Well ... it depend on your point of view ...
As a character you have few reasons:
1) You dont want to turn into mind flayer. And everyone keep reminding you that you have little time.
2) No metod is repeated twice, so you can never know if the previous metod didnt work bcs it was just bad one ... and this is the good one.
3) And finaly, since you can force your comanions to do that ... why the hells not?

You are perfectly safe while they are lying under someone's knife.
As a player there is one main reason abowe all ...
Its a main plot ... sooner or later you can either follow it, or just stop playing ... there is no third option.

Also, you cant quite avoid it, since whole game is revolving around that problem.
And i would dare to say that main reasons of existence of games is having fun ... so if you need to search reasons to keep playing anything ... you seem to have problem and should search entirely different kind of help. :-/
The companions are a bit forgettable. For each of them you get the standard "dark secret", most are jerks and uncooperative (maybe with a nice facade) and cooperate because of story reasons, but their ambitions are at best to get away from their "dark secret". It would be nice if they'd differentiate a bit more and had more interesting goals in the future. Having a healthy variety of personalities and past-oriented vs future-oriented companion quests would feel a lot more satisfying...
Even if BG3 needs to stay with the whole evil party vibe because Baldur's Gate is a hive of scum and villainy, why not mix in manipulative evil, evil in the name of good, evil but loyal, evil for a purpose, pure-monster evil, pragmatic evil, trying-to-convince-yourself-to-be-evil, slowly-slipping-into-evil, ...
Larian allready confimmed that we dont have all companions implemented yet ...
So i believe that there will be some differences.
Also you are talking about each having "dark secret" ... i wonder what is Lae'zels secret ... or what is Wylls secret ...
The others, well ... dont seem to tell everyone on the route their life story, but i dont know how is that a bad thing ...
"Hey i just met you and this is crazy, but you should know that i could turn into 20.000 kilotons magnitude explosion in any moment" > that would be stupid.

An issue (or opportunity) with most CRPGs: The companions feel isolated, with only the main character tying them together. More dialogue with more than two people would be interesting, to see how different viewpoints interact (requiring the previous point: different viewpoints). Part of why for example the Mass Effect characters were memorable was that they interacted more or less organically. That is possible with a relatively small cast of characters.
First you need to create all characters ... then you tie then together.
I personally would appreciate a "(sarcastic) Oh really, I'm shocked" dialog option at Astarion's vampire revelation. Or more fun: Make somebody else the vampire (though I suppose that's a bit harder)

There is a LOT more reactions that we need ...
Specificly a "(sarcastic) Oh really, I'm shocked" ... we could use in almost every second dialog with Shadowhearth, Lae'zel and Astarion.