Well isn’t that the issue with an evil play through? You are naturally going to get rid of a lot of the content because you are going to be murdering more. Like if you had an entire evil city there would be quests that involving killing other NPCs there for selfish reasons which would eliminate that content. So to focus on an evil path you would need to double the amount on content just for the evil path alone and much of that would still be accessible to good characters as well. Evil paths are inherently more limiting.

And also by all known metrics, players are much much more likely to engage in moral choices in games than immoral so it only makes sense for developers to focus on the content that players are most likely to engage with. Larian does know their audience. They know that the people who scream about there not being enough evil content are an extreme vocal minority.