Like what the title described, implementing this feature allows players to let the printer consume item rather than XP (would be even better if it's mixed, like requiring both items and XP at the same time) to get itself working.
For example I got a tech-themed pack where XP won't mean much, but I got a mod introducing some coins, like GregTech CEu Modern or Numismatic Overhaul, inserting coins might be more fun and immersive at this kind of situation.