It appears to me that the vocal representatives of the current crop of admins (meaning those who have become admins within the last year or so) have left far behind the idea that being an admin is "no big deal". They see being an admin as a big deal, and want things to remain that way.
I think adminship is a big deal. The amount of time we devote to talking about it is evidence to that. Things have changed a lot since Jimbo made that famous comment.
As I understand things, these admins view themselves as the indispensable shield between Wikipedia and the world, which is full of devious and persistent vandals. Without them (the admins), Wikipedia would fail utterly. Essentially, they carry the weight of the survival of Wikipedia on their shoulders.
And it's probably true. Of course, admins aren't the only such group. Wikipedia would fail utterly without people who write new articles, without people who do copyediting, without non-admins that fight vandals, without the people that do newpage patrol, without the people that help mediate disputes, etc. etc. etc. Wikipedia needs a very large number of different people, all of which are indispensable.
Each new admin, having just gone through a "rigorous" application and approval process, has essentially been selected for taking this sort of view. And each new admin has every good reason for maintaining or increasing the requirements for successive admins. In this respect, it becomes very like the process of hazing found in many clubs and exclusive organizations). This trend toward ever more "rigorous" requirements has led to cases of hazing on some US university campuses that were so severe the "applicant" died as a result.
Admins aren't a self-selecting group. Anyone can !vote on RfA. I don't know what percentage of RfA !votes are cast by admins, although I'd be interested if anyone has the statistics. Perhaps non-admins need to be encouraged to participate in RfA more to make sure such self-perpetuating requirements don't have such a strong effect.