If you've ever found yourself asking this question, you may want to check out our new PADS blog series, which is devoted to exploring the benefits of a constraints-driven PCB design flow. Steve Hughes explains in the first post the importance of rule definition and management. Read it on the PADS blog!
Steve also poses an interesting set of questions at the end:
What is the most challenging aspect of design rule/constraint entry and management that you face today?
Are there new and upcoming technological requirements that are difficult to address?
Let us know what you think, and stay tuned for the second and third installments of the blog series.