“I noticed in your other post you use Wisdom for your perception rolls and here you imply that Thieves are the class that uses Wisdom the least ... I don't necessarily have a problem with thieves' least likely ‘decent score’ being Wisdom, but I do consider thieves more naturally perceptive than the other classes.”Of course, thieves to have a additional aspect to their perception ability, that being their ability to hear noise. Although I've never done it - though I should start, I suppose - it would make sense to allow a +1 modifier on the die per 5% of hear noise ability. Thus, a thief with an 11 wisdom and a 20% hear noise would roll a perception check as though their wisdom was 15.
Putting that aside for the moment, I think where R and I differ is in the way we look at thieves ... I would guess that R holds the common perception of thieves inside the movie-making tradition. That the thief is essentially Thomas Crown, or John Robie, or any number of prestigious cat-burglars with, eventually upon reaching a high level, perfect reflexes and balance. Certainly, any of these would never fail to notice the slightest detail should it cross their path - and thus, they are deserving of a high perception.
I do not adhere to this model where it comes to thieves. Yes, I believe the possibility exists for a thief like this in a campaign - if the thief chooses to assign a high wisdom to their character. On the other hand, there are plenty of thieves in literature that fit perfectly into the model for a thief with low wisdom and perception. Fagin, for example, who isn't among the more terribly bright pennies in the box - nor the most perceptive. The same must be said for Pistol, Bardolph or Nym. Falstaff was drunk most of the time, and hardly as light with his feet or eye as he was with his tongue (you may examine the Merry Wives of Windsor for sources, if you like).
In short, there are thieves and there are thieves. Just as not every fighter is a duellist with two weapons, and not every assassin is an ugly sprat. Depending on how the player assigns his scores to his stats, the character is defined.
This is a chief problem I have with skills systems where players gain skills through buying them. The skills themselves are made according to assumptions made about what a character is and what is important. There's no room in the lexicon for a Pistol, as every skill is designed expressly to produce a Hudson Hawk. Every fighter must be a massive Conan; none can be a shrewd Petruchio or a brooding, angst-driven Elric of Melnibone. The mages must all be Galdalf - there is no room for a weakling Skeeve.
In short, two-dimensionality. If the skill is good for thieves, ipso facto all thieves must have that skill. Which I think is a big weakness of some systems.