Today I am doing a bit of design work under the two confidential projects I have on the books. If I didn't continue to actually design things for a living, I might start to wonder if all of the people in academia who have never designed anything which has been built, but insist they know how it ought to be done were right.
My clients want to spend the minimum amount of resources to progress projects to the next stage - why wouldn't they? The designers are often the one who has to insist that a certain amount of effort be put in to adequately control risks prior to signing off each stage.
The idea current in academia that design should start with an extensive and expensive modelling, simulation, and "optimisation" exercise betrays a fundamental misunderstanding of the commercial world in which all real design exists.
The idea that such an approach is imperative for reasons of "sustainability" shows that a definition of sustainability other than that of the professional engineer is being used. Sustainability is a highly politicised term, but the IChemE helpfully tell us what it means in our profession, with metrics: here.