You seem to be describing, basically, overengineering applied to visual design. For a developer, an example of equivalent behaviour is being overzealous about

You seem to be describing, basically, overengineering applied to visual design. For a developer, an example of equivalent behaviour is being overzealous about a specific programming paradigm. Things that can't be directly quantified in business terms (unlike "response time"). IMHO, it's about pragmatism and business sensibility versus artistic perfection. And it applies for both worlds. An argument from a more business-oriented visual designer could be, for example, about how some button color can affect conversion rate.