EBS volumes have a size, so there's an upper bound to the cost. Most of the storage is predictable, so if I try to allocate storage where the monthly cost of the raw storage is (ex) 10x my budget, I wouldn't have a problem with the request being denied.

For non-storage resources like EC2, network bandwidth, etc. I'd be fine with having a hard limit where everything just breaks, especially for stuff that's not production.

There could also be better, self managed quotas on resources. SES is a good example. AFAIK the quota is all or none across the entire account. IMO, it's not a good idea to give a user that needs to send (made up numbers) 1k emails per day credentials that can send 250k emails a day.

I have 3 AWS accounts. I don't keep anything in my main account. It's for billing only. I have a sub account for production that I try to keep pristine. I have a sub account for development and testing. It's the development account that scares me. I spend less than $50 per month. I'd rather have my whole development account de-allocated than get a bill for $1k.

As with all things just having the option would be nice, but it does not mean it is useful or a good idea for everyone to use it.

For personal stuff I would much rather a kill switch than a nasty surprise. For _some_ businesses, that is probably the wrong decision though.