I have mixed feelings about the amount of effort that was devoted to Yggsburgh and areas outside the dungeon, proper. I, too, would have preferred to see that effort devoted to bringing the dungeon, itself, to publication. However, I think I understand some of Gary's motivation for developing Yggsburgh and the upper works of the Castle. I think he was probably aiming for a Hommlet/Moathouse/Dungeon approach (i.e. the T1 model), but writ large as a magnum opus.
The T1 model is far from my favorite EGG work, but it's undeniably "Gygaxian" and popular with a lot of people. FWIW, I used to have a higher opinion of T1, but my tastes have changed, over time, and as I mentioned, Gary's "fantasy setting" vision and mine don't mesh as well as I'd prefer. Also, I'm normally not big on a lot of setting detail in an adventure module; I almost always have to change things that don't fit my campaign, and I'd prefer to have more interesting and less mundane material take up that space in a published adventure. (A dedicated setting book is a different story, of course, but even there, I like broad strokes with lots of room for referee interpretation and addition.)
All that said, there's a lot that I like about Yggsburgh, and it is positively loaded with adventure hooks. And while I certainly understand the point about focusing on adventure instead of economics, I'm also keenly interested in economics and monetary systems (especially those based on precious metals), so I'm a sucker for that kind of thing. I appreciate that the prices in Yggsburgh "make sense," overall (assuming you agree with Gary's setting assumptions). That is, they're internally consistent, and the rate for hiring a man-at-arms makes sense alongside the price for a meal and a quart of wine, and with the yearly incomes for the various social classes. Even if you consider that kind of thing a waste of time, I don't think Gary wasted much time on Yggsburgh's economics; the economic system was already developed for LA, and he just used what was already created.