2D background vs skybox

Hi guys

I'm generally creating medical training work in Unity and as such I don't really have a requirement for a truly 3D 'world'. Whilst my content is 3D, ie can zoom in and out in ortho and perspective, rotate around and pan, is it appropriate to just use a 2D background that's been created in photoshop for instance, rather than a skybox? Even something similar to this like at sketchfab, for instance. At the moment just a solid 2D colour is a bit depressing...

Thanks in advance