Analysis and scoring of a concept against defined requirements is one of the most important starts to a design. It sorts out the 'must haves' from 'would likes' and serves as a record of why decisions are made . Scoring against a benchmark clearly shows if a new concept gives sufficient benefit and highlights the concept most likely to succeed.
Once understood this tool leaves the engineer already equiped with a logical approach to design of assemblies. When used as an analysis tool for an existing design I have personally seen a reduction in an assemblies component part count of 77%
A DFMEA will highlight any design risk and be a tool to plan the implementation of design recommendations so as to reduce that risk.