I think the new standards are the result of the medical profession's realization that most people are not going to take the chance of putting their mouth on someone else's unless they REALLY care about them.
Nope. It is more because the studies prove that the blood has enough oxygen to make CPR effective for several minutes without the breathing, and, in reality, if you have not "fixed" the reason you have no pulse for several minutes, it doesn't matter anyhow. (Cold water drowning being a huge exception, but that is because of the hypothermic effect and the decreased oxygen demands)
FWIW, I am a rapid response team nurse at a 700 bed hospital in Minneapolis. Your mileage may vary, but
my mileage includes doing CPR over 200 times.
If you can't shock them out of a lethal rhythm or pace them out of a symptomatic bradycardia, all the CPR in the world is just going to make you tired. They changed a lot more than the CPR with the last revision of ACLS......