AWS’s on demand pricing is high but their reserved pricing doesn’t leave a lot of flexibility.

Why is it just 1 or 3 years? What if I only need it for 6 months or 2 years? Can’t I just get a discount proportional to a custom length of time?

Why can’t I choose the amount of money I want to pay under the “partial upfront” option?

Why can I only reserve some AWS services and not others? Why can’t I reserve a certain amount of S3 storage for example?