my rant about the Cult of Play Testing, but the two main points I wanted to cover were the delusion that pen-and-paper RPGs, like computer games, can become obsolete, and that tight, mathematically-oriented design is a Good Thing in RPGs.
Video games become obsolete when the hardware or operating system they were designed for is no longer available and the game was never ported. The hardware for your typical tabletop RPG is some kind of writing tool, some kind of randomizer, and the people to operate these. The operating system is called "your brain". Your brain is not obsolete, and simple writing tools and dice (or cards) still work the same way they've always worked for centuries. Batteries don't go dead in dice or pencils. Treating tabletop RPGs as if they were computer programs, requiring frequent updates and a rigorous design process, is not only ridiculous, but I suspect mostly about ego, putting on airs of being some great designer.
As for tight, mathematically-oriented designs, the problem with repeated tweaking of numbers to get the perfect system, meshing perfectly and rationally with all other components of the system, is that it produces boring RPGs. Plus, since those components you are tweaking are really a matter of taste, it's not really the perfect system, is it? Just somebody's temporary answer to the question "how do I want to play?"
The thing is, despite the name, roleplaying games are not games; they're pastimes. They are not meant to be rigorously-defined activities with a clear objective, but loosed "play" with transitory "in-fiction" goals. The most fun in an RPG happens not when the system performs as expected and players are able to demonstrate their mastery of the rules, but when unexpected surprises happen. That's why the GM's rulings are so important: not because they fill in gaps in the rules, but because they keep the game from being just a pen-and-paper version of Diablo.