There are many tools and processes that support organisation and people development, and psychometrics and apptitude testing are only some of them. These tools are as good as how you use them. I have heard of many stories ending in people going miles out of their way due their reliance on their SatNav system - Similar to SatNav's, these tools give valuable information that could improve the learning and development process; and it is how the information is interpreted and used that is critical.

Individual development:
During a coaching role, SHL Occupational Personality Questionnaires (OPQ) can be used to support the process of self awareness. The output from completing the questionnaire help people consider their way of work and their behavioural style; how they approach their job rather than the ability to perform the role. There are other tools available to increase awareness and knowledge of a person's motivation, capability, competence in their role.
 
Assessment centres:
Psychometrics and aptitude tests can be used as a valuable source of information when assessing suitability for a particular role during the recruitment process. If you invest at this point in the recruiting process, whatever the role, you are more likely to attract a candidate who is 'right' for you organisation saving you time and money in the future.  

Development centres:
I have used Psychometrics and aptitude testing to support developmental programmes at all levels. They give candidates the opportunity to explore areas for development and help to produce robust plans of action.