Timestream minimum 100GB magnetic storage

I just want to raise that this 100 GB magnetic storage minimum on AWS Timestream is a lousy thing to do. I could understand eliminating magnetic storage from the free tier. But a 100 GB minimum seems arbitrary - it's not usage based, and if something about the system requires storage space to be allocated in 100 GB chunks that's kind of an internal architectural problem, not that of the end user. It's weird that on one of my accounts I'm using 85 kbytes of magnetic storage, but I now get to pay for 100 GB. $3 per account doesn't really matter (though I have three accounts, so it's $9).

Maybe this just warrants better explanation.