The published material didn't mirror the writer/designer. In other words the dungeon master Dave Hargrave was very careful what & who he put into his games. The needs of the campaign are dictated by the players & where they're taking the campaign setting. This is even true for my home campaign using an OSR system or two.
Campaign & game balance are very different things, Arduin's material seem like its not balanced & beyond a certain extent its not. But the world of Arduin itself? Well there's an internal world setting consistency to it. Too much of it & you get the dull hum drum efforts of 'Wizbros' efforts over the last 10 or 15 years.
Get too much game balance in your systems & the spark of the material is gone in a puff of game design.
Just a stack of books without players!
The players are the deciders of the direction of the campaign world not the author & often times they come to the table with expectations that the dungeon master may not be aware of. This comes with the ideas & exceptions that the DM has to bring by communications with the players. While this may seem like common sense its often seems in my experience that the players & dungeon masters can be at odds. In the Arduin fan group on G+ I'll get Dave Hargrave's home games weren't as wild & crazy as Arduin reputation is among some of his fans. Yes this is true but players coming to the table crave excitement, adventure, & just more then a wee bit of the crazy.
Knowing where & when to apply 'the crazy' is a bit of a fine art unto itself. The fact is that keeping it in the game is fine as long as it applies to the adventure. Gamma World often did this in spades & when correctly done in an original Dungeons & Dragons game it works light years into making the game a lean & mean science fantasy machine.
I love plane & dimension jumping, playing with the fires of Sword & Sorcery, & generally having a solid adventure either in an unexpected dungeon or an adventure location. My current game uses events of real world history mixed in with a plethora of science fantasy elements. The players weren't expecting it but have been rolling with it much to my happiness but it was their choice.
Choice & communication among players seems to be the best of both worlds in both old school & OSR play.
This may often be the result but the players will thank you for it. The poor, dead, dumb bastard!