I don't see them adding a 1 day option any time soon. 3 or 5 day maybe, as mentioned, as they could price that at a decent price... But a 1 day roaming package would likely end up being priced terribly (it certainly won't be 1/10 the price of the 10 day), and people would end up just complaining that it's a horrible price.
What I would rather see (but which I also don't see as being very likely, as maintaining it would probably be a bitch) is a 10 day roaming package with the ability to turn it on and off at will from self-service, so you don't have to start using it immediately when you buy it, and you don't have to use 10 consecutive days, but rather can use the 10 days whenever you want.
