Hi Folks,
Here's eBay's page on the 1-day, which states "The 1-day listing option is not available for Fixed Price or Stores format listings. However, it is available for Auction format listings
which include a Buy It Now option.
http://pages.ebay.com/help/sell/1-day.htmlI recall the rule for certain categories, but it would appear this is (by Help) now a blanket rule for auction format.
Danno
Edit: In thinking back over last several months of rule changes, my best guess is the rule is tied to one of those changes that set the restrictions on number of concurrent identical items limit to 15 (which follows on the same page). Obvioulsy, it's a way for them to get more fees on the 1-day. And, you can tell I just looooove fees, fees, and more fees.
In looking further, the 15 items limit was lifted in June, but a full text of the rule changes might have more info.