From my very early days with WinMo (Motorola MPx-200 anyone?) on through to v6.5, the appointment snoozing function is something that has always defaulted to only delaying the alarm another 5 minutes. I've always had to fix it with either some third party tool or a few registry judo chops.
Android has the same "issue" but there is a great couple apps that handle it well. I have never used an iPhone and never integrated my dear old gen 2 iPod Touch with Outlook, so I don't know if it exists there also.
And I doubt it will ever be addressed because it isn't a glory feature, so it isn't going to get any love.