<sarcasm>Yes, I really want the title of the document to be printed out on the receipt printer, along with the URL of document and the page numbering. I thoroughly enjoy seeing professional receipt layouts ruined by the browser's default headers and footers that get pasted to EVERYTHING.</sarcasm>.
Sarcasm aside, what if I don't want Page X of Y, I just want Page X?? What if I want to use Roman numerals? Or even better, since html 5 has the section tag, what if I want the page numbering to restart with each section? Why should print layouts be shackled to browser defaults? They shouldn't.
But can you suggest another way to deal with page numbers?
I can certainly see merit of having :first-page, :last-page, :odd-page and :even-page properties. I'm less convinced by the need for position:pagefixed, but I can imagine situations when it would be useful.
pagefixed is primarily for those pagination headers and footers, or potentially for a watermark. It allows them to be styled as wanted.
The background properties I am not so keen on - I don't want to give authors the option to waste my printer ink, whether they think it is a good idea or not.
Your personal preferences on ink use aside, it's a major PITA when designing an application that needs to print reports where striping the tables with #eee would be a GREAT help on appearance, just to name one. I can see understand disabling background printing with screen media - this behavior predates CSS, but if a print stylesheet was prepared than presumably that was taken into account in the design.
So if a printer stylesheet has been prepared it should be used. If you don't like the ink usage then prepare a user stylesheet to override or copy & paste to word. I could live with browsers turning background printing off as an option per page, but for print stylesheets it shouldn't be the default.