The 90% is silly... how can consensus be two different
percentages? It can't
be both a vote and consensus at the same time. People either need to admit
it's basically a vote, with different requirements for RfAs and RfBs, or
change it so it's the same for both. You can't have both a voting % AND
consensus.
It's "rough consensus", which basically means supermajority with a
slight weighting of votes based on reasons given. It's not a pure vote
(at least, it's not meant to be), but it's certainly not consensus. We
rarely get a true consensus on any Rf(A|B) - it would essentially
require 100% support (there is a difference between consensus and
unanimity but with a format like RfA [which discourages discussion],
that difference is minimal).
An interesting factoid: I work on three other wikis
as well as English
Wikipedia, and they all keep the same % for bureaucrats. I don't know why
English Wikipedia is different. As I said, it's very silly, when all they do
is the job of a calculator (and when they don't... guess what, it causes
controversy!)
The requirements for crats should certainly be higher than for admins
(since crats need to be admins too). That can be done either by people
being harsher in their votes, by the required percentage being higher,
or a combination of the two. Since people are a lot harsher in their
votes, the percentage doesn't need to be much (if at all) higher - 90%
is probably a little excessive.