Do you know people who made their own custom games out of the underlying system of GURPs or DnD? My friends just created stuff off of the dice rolls and overall battle system. We didn't use any of the premade characters, towns, stories, quests, etc. The roleplaying aspect was totally reliant on whatever the person made as a character. We had races and such that weren't even available for character creation normally (or even in the game period) as something the player could use.
Sure (not that I'd suggest either of
those systems). Hell, I made my own
system out of whole cloth, that blew
away most, as to combat realism.
Moreover, did a bit of pure free form stuff,
without dice rolling, or clear systems.
Still, I
would never have hit upon the package that
they were selling, in terms of how to lay down
a mood, for a particular type of game. Even trying
to translate those lessons to other systems never
worked too well (more a matter that when one is
preparing to run a game, they are brushing up on
the rules, so the flavor of the manuals rubs off).
The closest I came was in a Pendragon game,
where the reason was really a model castle that
I built. That, and lighting, made one session just
burn into everyone's head - to the extent that,
until Vampire, we would just be in awe of that one
night.
Strangely, I found larps to be LESS conducive than
the tabletop version of the WW stuff. May just be that
there were too many people, not well enough trained
to be acting.
As to premade scenarios and such, I see no real problem
with them. They provide a lot of grunt work, in terms of
a detailed background. Having a goodly number of NPC's
set ahead of time is much easier. I'm lazy, so I tend not
to populate my world fully, otherwise. Things don't mesh
as well, nor do ideas ferment the same way.