I'm curious about this part as several people have mentioned something along these lines. What exactly is saying that the Innkeeper has a magic crossbow and his daughter is a level 4 Ranger, or that the Blacksmith down the road can churn out a Longsword +1 for a modest fee? I'm very curious, and I'm not trying to cherry pick your post, just trying to zone in on the matter.
I am glad you asked. As I pondered it, it helped clarify something in my mind about worldbuilding.
First off, I have no problem with worlds that have a high level of magic items. Ye Olde Magik Shoppe concept is just fine by me. FR certainly has that concept, especially in 3e with the Thayan Enclaves. From my origin post, I mentioned I was seriously considering setting my flag in Eberron.
So what does quoted above imply about the world? That is a very good question that I feel FR has never fully answered. As I pondered it, when you make as setting there are a number of things that have to be considered. This is not an exhaustive list, but three that come to mind are:
Tech level - what can people make
Magic level - The level of power influencing the course of events by using mysterious or supernatural forces.
Mystic level - how do the gods interact with the world.
FR appears (to me anyway) to be:
Tech - Medieval
Magic - High
Mystic - High
What solidified in my mind when you asked the question was not about the Magic level, but the Tech level. When you say people can make magic items, commission them, and perhaps have enough traffic to even have a shop that buys/sells them - that is a Tech Level question. The source of the power might be magical or even mystical, but the process of being able to formulaically make and replicate an item is technological.
For example, I have little to know direct knowledge of how my smartphone works or even have the faintest idea how to make one, but I can easily use it to do what I want it to do. It might as well be a magic item to me. I am sure a farmer has no idea how a Decanter of Endless Water is created or works, but you tell him three words and he would have no problem using it. If Decanter of Endless Water can be reliably made in the world, that is technology IMO. It seems to me a farming community with a couple of retired adventurers would trade in a few +1 swords and daggers to get a reliable endless source of water.
So back to the quote: the fact that the barkeep has a magic weapon does not necessarily say much. The item could be from another time and place - perhaps like Hellfrost (from my post) that people cannot make them anymore. The fact that a blacksmith can make a magic sword implies to me that their should be a ton of "practical" magic in the world. The world should feel more like the late 1880s or later in our world, but perhaps "magic" is the driver vs. say electricity, steam or oil. How cheaply, easily, and "miniaturized" the creation process is will drive if it feels like 1880 vs. 1980 vs. 2080.