You only give forums and beta access to people who have donated $16 or more, while you send handwritten postcards to people who have even pledged the lowest amount.

Now, I'm not sure if you plan to spend a dollar out of every $4 for international postcards, but it would be nice if you could give access to everyone who donated.

Two reasons for that - not everyone lives in a first world country (and expects postcards) and secondly, even a dollar committed to the idea of a software is more than most people.