Frankly, it's not fully fair that clients ask designers to improve the client's metrics, to improve conversion rates, and increase their revenue WITHOUT the designer having some form of feedback mechanism that can be used to optimize design BEFORE it is launched to the public.

This is clearly a different way of looking at the situation. But I think it is appropriate.

I know as a fact that designers can produce more effective material when they are provided direct, objective feedback on the effect of their design decisions (typically ranging from 42% to 300% increases in conversion rate for simple designs, and up to 2000% increases for more involved web pages) than when they are instead forced to just rely on A/B split tests using click-based metrics. Getting feedback from launching a new design and watching click-throughs go up, down, or not do much of anything is really too late and isn't very informative (so 15 different things were changed in the redesign... which one was responsible for the clicks going up or down???)

We work with a lot of agencies and design firms, and definitely want to work with more, but we've seen a number of end-clients shoot down the design firm's recommendation to make use of eyetracking feedback because the client instead expects the designers to just do a great job no matter what.