I believe you have said that if Obsidian made Pillars of Eternity 3, you would probably push for it to be full 3D rather than 3D characters on 2D maps. If that happened, would you allow full rotation of the camera or continue designing the maps for a fixed perspective ? It seems to me that this limitation, when you know how to work with it, can be really helpful to clarify exploration and combat.
I would probably use a fixed perspective with scripted sequences that break the common convention. As a player, I don't really like playing with the camera as an element of gameplay, especially in "iso" view games. It's okay in close 3rd person, but in a Pillars-style view, I think it just makes busywork for the player to find the things that the designer hid (intentionally or unintentionally) because they can't design for a fixed perspective.
However, I do think there's a benefit to the designers and artists scripting a change in camera perspective for specific sequences when it makes dramatic/artistic/gameplay sense. If you want the player to go around a long curve, you can script the camera to rotate around the terrain as the player moves the camera's position. You can even change the FoV, pitch, etc.
In the end, I think that designers and artists create the best experiences for players (in terms of performance, gameplay, and vibes) when they design for a "known" camera, not one that the player can (and often must) rotate manually.
