“We’re arguing about the game engine, let’s argue about the game,” Nesmith told VideoGamer. “The game engine is not the point, the game engine is in service to the game itself. You and I could both identify a hundred lousy games that used Unreal. Is it Unreal’s fault? No, it’s not Unreal’s fault.”
“Gamebryo is no longer a business, it hasn’t been for a while,” Nesmith said. “But that engine has been constantly tweaked, updated and refined to do exactly the kinds of games that Bethesda makes: The Elder Scrolls, the Fallouts, Starfield. It’s perfectly tuned to that kind of game.”

Skyrim Lead Designer admits Bethesda shifting to Unreal would lose 'tech debt', but that 'is not the point'
Skyrim lead designer Bruce Nesmith explains why Bethesda switching to Unreal may not be the upgrade fans think it would be.