Perhaps you should buy a few and donate them to developers.
Er, If I was asking for some bizarre piece of hardware to be supported, then your sarcastic comment might have been warranted.
The fact is that USB hard disks are hardly thin on the ground, and they use the same drivers as USB Keyfobs.. And who works in IT and doesn't at least have one of them?
If I had any spare, I hapily donate some cash to those who are developing SME. But as it happens I have dificulty paying my electricity bills!
If I had the skills to develop this feature myself, I would. But my skills lie in other areas, and I've produced a couple of howtos. I'm also in the process of developing several more, and a full contrib once I've got my head around the way the server-manager panels work. I am NOT one of those people who ask and never give anything back in return.
SME servers are frequently installed in places where money is scarce, so in this day and age, with the amounts of data that regularly needs to be backed up, tape drives are just too expensive to be an option.
The fact is that a 160GiB USB2.0 hard disk costs about £65, wheras a Tape Drive capable of that kind of storage is £1,500, and the tapes for it are about £45. You do the maths.