This is an isolated demand for rigor. Of course we don't know exactly how much each line item on the Larian budget costs. We don't NEED a detailed description of the budget to know that stuff costs money. If its not free then the budget for it represents an opportunity cost, because that money could be spent elsewhere.
Yes, we know that it represents an opportunity cost.
But the assertion being made is that it was a large opportunity cost. Both in terms of money as well as manpower.
Which would NEED a detailed description of budget as well as workload distribution to evince.
All we know is that SOME money was spent on it and that the people who worked on it did not work on SOMETHING else.
We don't know HOW much money was spent on it (And whether it would have been enough to fund any other tasks), nor if the people who worked on it could have worked on something else (If there were no other tasks suitable for those people's skillsets, then their time wasn't pulled away from anything else)
Ergo, to state that the development of this content was to the detriment of other content would require the burden of proof to be on those who claim to know exactly how much of an opportunity cost such an undertaking actually was.
One can state their wishes of having X thing instead of Y thing, for sure, but that doesn't mean it would actually fit with how the game was developed.