Regarding him getting less updates than other companions, I kind of get it from the standpoint that:
1. Arguably he was the least broken romance on release. We can be suggesting all the improvements above but as we kind of agreed to begin with, he already has a great romance. Meanwhile, we still cannot kiss Minthara, she says she will come to us at night but never does and Gale went from harassing us to giving us the "we are not that close" treatment betweeen patches. He is not a priority right now, but I am sure things that need fixing will be fixed.
2. Someone did a summary of the time each companion has in dialogue/personal quests and Astarion's story is iirc 1.5x longer than Wyll's. We have to remember that this is *technically* not an Astarion dating sim and it is at this point more important to improve/add stuff to other companions to improve the game as a whole.
And regarding him becoming a monster post ascending - that is the whole point. Disregarding dnd lore and how true vampires should behave - if we only look at psychology... It is a real thing that abused people can either heal and break the cycle, or refuse to heal and be doomed to repeat it. In ascending him, you are confirming his core fear - that he is not enough just as he is, that he needs to become more powerful to earn respect. He does not even know how to be a better vampire ascendant, because the behaviour blueprint he has is shit. Meanwhile, if you convince him not to ascend, you are showing him he is worthy of love just as he is, he does not need to become an improved version because this version is what you love.
You also get multiple warnings and foreshadowing that this is who he will become after you do it. I'm fine to leave his ascended story as is - although for you feral ascended fans, I do hope they fix the camera . If Minthara's scene is as explicit as you guys say, then I see no reason why we have fade to black in almost every other romance. Maybe it should be a toggleable option? Like showing full nudity is?
+1 on all this, except everyone's story is longer than Wyll's and I don't think he got anything new this patch either. Apart from some bugs.
I once saw someone describe Minthara's scene as softcore porn and honestly that's accurate. None of the male companions come even close (though I haven't seen Halsin's). So it's interesting that they felt the need to censor ascended Astarion.