Why do US universities have strict formatting requirements for dissertations? Recently, I got a mildly panicked email from a friend/collaborator who was preparing the final manuscript of his thesis. He had just noticed that page numbers were a fraction of an inch closer to the page edge than the regulations of his university specify, and he was concerned that the lady in charge of filing dissertations would notice and reject the manuscript. This concern wasn't unjustified: I personally know a couple of people who had to reprint their dissertations at the last minute because they had the type of formatting errors that you need a ruler to notice. 

In the end, I was able to tell my friend how to modify his TeX markup to avoid disaster, but I was left wondering: why are (some) US universities so obsessed about aspects of a dissertation that nobody will ever care about, or even notice? I did my PhD in Europe (Netherlands), and nobody there cares much about the formatting of your dissertation, so long as it doesn't look silly.
I think this is a historical issue more than anything else. Until quite recently, dissertations were usually sent for microfilming, microfiching, or both, for later reproduction and distribution. As a result of this, they needed to be carefully formatted so that they would reproduce correctly when photographed. Thus the requirements for font size, margins, line thickness in graphics, positioning of page numbers, and so on.

In recent years, this has not been so important, but that doesn't mean universities have completely relaxed the rules regarding formatting. There is definitely an interest in having a consistent "look and feel" for theses from the same institution.