There seem to me to be a lot of "oughts" in here. I think we agree that regulators ought do their job, even it that seems more the exception than the rule. It is, none the less, generally true that very low interest rates for a long time and with an expectation that they will be low for a long time is an invitation to carry trades and to bubbles. These conditions might not "cause" bubbles, but they certainly enable them. Perhaps human nature in a lightly regulated low interest rate environment with run amok finance doesn't "cause" bubbles either, but there will be a high correlation of the creation of bubbles with such conditions.

"It is not necessary to have hope in order to persevere."