Imagine the typical scenario - we've all been there:
You do some testing with a reserved IP.
Before the initial 24 hour minimum age is up, you are about to embark on a 6-month internet-less holiday with some super-model.
You are unable to cancel the IP.
Question: Do you cancel the holiday so you can cancel the IP later, or do you go regardless?
More seriously, I'm forgetful. It would nice to be able to "delete" an IP at any stage.. Actually, restriciting what you can do based on countdowns - a "come-back-later" requirement - is bad, in my opinion.
This isn't about the charging... What I mean is, delete it, but still charge the minimum 24 hours... That's cool. Or, if it's a technical thing, shove the request onto a queue, so I can take that well deserved holiday! :-)