Hussar
Legend
Its what the expert class is for, firstly. Just like the aristocrat class is to model those that are born into wealth, the expert class is there to model true professionals. As for the level, I almost always make any man of practiced skill about third level. It just feels about right to me and I don't buy into the theory that 3rd level is that special.
I only ever use 1st level commoners for those that don't do a lot of work, aren't especially trained in anything or are just out of their teens. I even make a typical farmer an expert as there's a lot of things your average farmer knows how to do. Commoners are good for modeling a serf class but, honestly, most D&D worlds don't have a large serf class.
As for demonstrating the ability achievable at first level, its possible for any character to be really good at one thing at 1st level, but other skills will be less stellar. But if thats what you want in a character (a really diplomatic queen for instance) then its pretty easy to model that without getting into high levels.
Fair enough. Just so's you know that this is your rules and not what actually stated in the game. The actual demographics in the DMG pretty strongly contradict this, and, also, the description of the actual class of expert contradicts this as well.
A blacksmith no more needs to be an expert than a farmer does. The Craft skill is the only skill he actually needs. And, again, going by what's actually written in the game and not your specific campaign world, 99% of the population (or actually quite a lot more) is, in fact, 1st level.
But, your second point is interesting. Ok, I want a queen who is diplomatic, has good sense motive and is pretty darn intimidating when she wants to be.
How do you do that without adding levels?
See, this idea that our Queen example has only one skill is not something I said. Diplomacy only affects others. It doesn't actually help me from being affected. Thus, what I said earlier about our 1st level Queen being totally dominated in skill contests by others. Sure, she can use diplomacy to make others do what she wants, but, she's completely bamboozled by any higher level character.
This doesn't really fit with my idea of this queen.
KM - sure, you can totally simply whack on a great honking circumstance bonus. But, again, I STILL have to stat out even a 1st level aristocrat. To me, the idea that NPC'S MUST be built the same as PC's is a weakness in the 3e ruleset because it just adds on so much work to the DM.
In 3e, by the rules (what I do in my own game is fine, but, I'm actually talking about RAW, not my game), I can't just say, Queen Victoria has +20 Diplomacy, +15 Sense Motive. I have to build that. Even if I can do it with a low level character, I still have to take the time to figure it all out.
Which is exactly the reason I never used classed monsters. I'm just far too lazy to spend an hour statting up some NPC, when I can use a pregen monster in 5 minutes.