Complexity of current quant models is a practical irrelevance!!!

[themarketprofessor]

I believe when a model simply serves its purpose if it serves us as a rational way of explaining what happens when the variables change and affect future cashflows. Simplicity is bliss! Complexity is enemy! Why then recent quant generations have dwelled onto unjustified complexity from models, like Heston vol model, Dupire's local volatility, to models like Stochastic local volatility and to Uncertain Volatility model?

Regarding pricing exotic options, can someone give me a hard cold example of a situation when we need a complex model (eg local vol, stoch local vol)? And explain why it is useful and beneficial? Why should i buy such a model?