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For example, if the Elves of Ravenholme have a signature underhanded twirling dagger throwing style, it's less problematic to explore how that can arise from a combination of feats rather than add a new feat with prerequisites "Elf, Rogue, origin Ravenholme, wielding a dagger". Rather than introduce 20 new feats for Ravenholme, it'd be better to discuss one feat that twirls weapons and can be used in many interesting combinations. Sure, that means that the crunch magazine articles need to be structured differently (around a technique, not a fantastic location), but it allows the same number of interesting choices while having far fewer options.
I'm much happier with a label (not pre-requisites) 'Elf, Rogue, origin Ravenholme, dagger'.
When I go through my decision tree there are many opportunities to sort or ignore this piece of information.
If I do not use Ravenholme or their elves than I can discard this information. It is like the library is filled with books that I will never read despite being written by fine authors but I only have so much time and effort to spend on things. I manage the glut of books by deciding non-fiction is not stuff I am currently interested in reading.
If I am not currently looking at making a Rogue character than again, I can choose to set the feat aside until I am making a rogue.
If I have met all the other conditions than I can decide if I am looking for a feat to improve my dagger techniques or decide if something else (singing, wilderness lore, stealth) might be what I am hoping to improve in my concept.
I can also decide if this dagger feat compares better or worse against other dagger feats and weapon feats.
So: fewer powers & feats, but no fewer choices by virtue of more generally applicable rules. Side benefit: this means that the individual rules can be worked out in more detail. Want to make a lightning bolt with an area of effect that doesn't quite fit the standard areas? Now you have space to describe those specifics. Want to describe the effect of a powerful strike on nearby objects? Want to make a tactically interesting surprising roundhouse strike by forcing attacks to resolve in clockwise or counterclockwise fashion, allies included, but without the ability to strike through solid terrain so that the user needs to take into account the state of the battlefield? You've got the space.