What insight is being gained by going with the more complex model? You can work out a lot using classical EM and predict a bunch of cool optical/diffraction phenomena without a lot of math, and the math you do is crystal clear. QFT or even just QM+time-dependent perturbations are a pain in the ass in comparison.

I wouldn't call it inaccurate at all. I think it's a perfectly good model. You can explain the phenomena otherwise using a more detailed model, but you don't need to.