Honestly, nothing stops people from using these families as just good inspiration for villainous samurai without ever mentioning the word "Spider". And even if someone decides to have a Spider Clan, they can only mention a few of the families listed, while silently ignoring or retconning the others. Every GM has their own personal Rokugan after all. The more ideas, the merrier! The only thing that bugs me is that the Spiders are pigeonholed as inherently anti-Haneti and anti-Rokugani, when you could imagine at least a few Tainted individuals who is willing to follow the "two masters" idea preached by the AEG Susumu, that one can both serve Fu Leng and Rokugan (probably by plotting against foreigners). But then again, instead of complaining, I could quietly add that personal detail to the Susumu family, and probably even play up how delusional they are in thinking that they could serve two Masters without suffering any repercussions.

Before I start, I would say that if the GM says that the Imperial Families get a +1 Earth bonus instead of a +1 Air bonus, that's totally okay. It's your Rokugan. --- I confess to not reading the stories, but I still think the bonus is probably correct. The bonus is a +1 to Air, which does imply a lot of things, but doesn't mean that people have to be competent in Air-related stuff and not competent in Earth-related stuff. You can have characters that get official training in Air, enough to do decent in courts, and then decide that it's better for the Empire to stop studying Air and instead focus on Earth. The Imperial Families "clan" gets a +1 Air bonus. But you have to specialize in one of three specific families...and two of those families are willing to embrace Earth. The Seppun, in particular, shun Air entirely. Miya: +1 Air or +1 Earth Otomo: +1 Air or +1 Water Seppun: +1 Earth or +1 Void Furthermore, each character has the right to influence their own curriculum to some degree. In Question 4 of the 20 Questions character creation system, players are asked "How does your character sand out within their school?" They can pick a trait that gives them a Ring bonus as well. If someone is sympathetic to Earth, they would pick "Thoroughness, patience, and calm" and claim a +1 Earth bonus. And maybe most Imperials decide that maintaining the empire doesn't require the customs, traditions and appearances that Air support...that it requires the practicality that only Earth offers. Perhaps Imperial academies stress to their students that it is important to study Air officially...and Earth unofficially. So my guess is what is happening in the fiction is that most Imperials are getting a +1 Air from their basic training, but doesn't try to get more Air bonuses after that. They either get +2 Earth (if they are Miya or Seppun) or +1 Earth, +1 Water (if they are Otomo). That's enough to explain why they might flounder when actually using their Air ring, while doing well in non-Air related matters.