The short answer... students and teachers.
They need them to have room for writing comments when grading essays and such. But does that really mean the rest of the world must suffer with a default margin?
I personally don't think that page margins have any place in the modern business world.
Sure, back int he 80's we needed them for dot matrix printers (didn't want to print over the track holes or page perforations!) and for leaving room for binding all that dusty paper together before stacking it in filing rooms to serve as a fire hazard, but never to be read again.
However, in the modern world, there is little reason to actually print much on paper. Most reports, for instance, are printed to a PDF file and emailed or otherwise stored electronically (never to be read again :) ). Modern printers can print right to the edge of the page, so page margins have become more for aesthetics than function.
So why does pretty much every application (eg. office, SSRS, etc...) out there that designs things for printing still assume we need a default margin? Why not let the default be zero (or some tiny number like .01in) and let the person entering the content add a margin if desired?
If someone knows the answer, I would enjoy your comment.
