You know, there are alternatives between a sudden total cut off of service and nothing at all. Some mechanism to prevent sudden, large unexpected bills, yes, that’s desired. Notifications are not enough.
A lot of people have provided tons of examples of follow ups by vendors in this thread where novel large orders are double checked. AWS could provide any manner of preventative policies and cost controls but they choose not to.
Given the choice between blowing 2x past the planned opex and an outage, yeah, there are plenty of applications where the latter is preferable.