I think the biggest problem with cut content is how it has impacted some of the main companion quest conclusions and other relevant main story plot points. Every game has cut content, maybe you are cutting side content to better polish up existing stuff, but when you start cutting critical content that resolves quests, or frames villains more appropriately, then it hurts companion stories and the main story itself.
There is evidence, through datamining, of cut content that specifically resolved companions currently/seemingly unsolvable quest chain.
There is evidence of cut content to the upper city where Gortash was supposed to be, thereby providing a de facto 'additional act', which would have chopped up the pacing of the game a bit more in Act 3 where it is all a jumbled mess of a million random side quests/busy work all while you are given a sense of urgency for the BBEG.
There is evidence of cut areas that would have resolved and built up a lot more framing to the main story (e.g. Avernus).
There is evidence of cut content specifically related to the actual epilogue for the game itself.
So it's not just cut content, as every game has cut content, it was cut content that specifically resolved currently existing quest chains in the game that are now rendered unfinished and unsatisfactory and literally make the game feel explicitly unfinished.
My personal theory is that so much was changed in the lead up to release, that they had to cut a lot of this other stuff to focus on the massive re-writes, e.g. Daisy/Guardian, Wyll's entire re-write, Karlach's and Halsin's inclusion into the game, etc. They have to pivot to these re-writes and trying to frame them in the existing story and had to let a lot of other stuff go, but that only served to make all of the late additions either feel unfinished, which they literally were, and/or create a lot of plot holes with late inclusions to the main plot that served to weaken the overall story itself. This isn't hard to believe because the
Guardian is revealed at the beginning of Act 3, the weird mandatory illithid/Orpheus false dilemma, Act 3, Gortash and Orin's inclusion feels extremely abbreviated and inconsequential, they feel like minor obstacles/mini-villains. I could be wrong but I felt Act 1 was setting us up to resolve the tadpole situation by Act 2 and that the Chosen Three were the big obstacle from there on out, hence the Ketheric arc in Act 2, but then they changed all of this at the last moment to then go back to the Netherbrain/Illithid plot last minute.
I can only hope we get a real revision to Act 3 and a restoration of at least some of the cut content to make the main story, and critical companion stories feel whole. I don't think this is that far fetched as we are in a very similar situation to when D:OS2 was released in terms of final act content/story and certain companion quest lines.
