My take on 3D in Defold is that using 3D models can greatly enhance a 2D game. I’m working on a 2D game now in which most game world objects are 3D models. It allows for smooth rotation of objects that would otherwise not be possible (or using a lot of texture space with individual sprites).
In another 2D game I’m working on, the camera is slightly tilted so that more of the world ahead of the player is visible, making it easier to navigate the 2D space.
In short, I see 3D in Defold as something to complement the 2D, not to compete with it.