By that logic, 0-conf is also fine for day-to-day transactions, and indeed that's what every physical btc-accepting retailer I've ever used does. I don't see a rash of double-spends against coffee shops as particularly likely.
As to litecoin specifically, there's essentially no use-case where a statistical 2.5min avg conf is acceptable but a statistical 10min avg conf is not.
If you rent a rig on Betarigs, you have to wait for 1 confirmation before you can start hashing. That takes 10 minutes avg. right now because only Bitcoin is supported. If they would implement Litecoin payments as well, you could get started in 2.5 minutes instead. That's a lot faster, when every minute is important.