These are just my personal observations and perspective..
When I worked in recruitment (for 10+ years) I worked with numerous very successful international companies who were not interested in using psychometric or cognitive testing. However, some of the companies had very developed interview processes and there was clear evidence that it was serving them well.
Of the companies I dealt with that did use psychometric and/or cognitive testing, I can't recall one instance where the test results were ignored and the company went ahead and hired the individual. In fact there were many instances where the hiring manager was very keen to hire the candidate but was unable to do so as a result of the testing. I'm sure in some cases the "baby was thrown out with the bathwater".
If "even the best tests can only account for some 40% of the variation in performance in employees" then perhaps it could be argued that a rigorous interview process could be just as effective, or possibly more effective.
While I am sure the tests have some value, particularly in challenging perceptions that have been subjectively influenced (
The Dufus Factor), there is a danger that companies use testing to make up for a shortfall in their recruitment expertise, or testing can make companies or individuals within, a bit "lazy" when it comes to developing their interview techniques.
