[Ars Mysteriorum]

I don't think rules supporting roleplaying are essential to the roleplaying experience, but at the very least I like to see a system that is willing to leave some "loose threads" to be decided by GM discretion based on the wild and crazy situations players get themselves into and their motivations for doing so.

What we see in the d20 system is a locked box of sorts. The designers have set out to ensure every loose thread has a reference within the rulebook, leaving less to GM discretion as designed. Yes, houserules can "fix" everything, but we are discussing the game as designed.

Because there are no "loose threads" to refer to, player innovation is limited to options within the thoroughly marked boundries of the system. Actually playing a role becomes more like dressing for the specifically defined action, which precludes the potential for highly innovative actions with complex motivations that are summed up with a simple, loosely defined roll left almost wholly to the GM's determination (the new Basic RolePlaying system handles this nicely with Effort, Endurance, Idea, Agility, etc. rolls that handle reactive and improvised situations).

Anything can be a roleplaying game, I agree, but I think people like to see their nifty ideas have a greater impact than a rather lackluster +x to a narrowly defined action.