No it is not. The IL rule was voluntary, and I hadn't ever heard it changed. Flatlander's lauching their canoes and kayak's at the local lauch here in WI ~month ago, were not defaced with a 3" high, 1.5-2' long string of numbers. Folks only do it, to avoid being pulled over for a "papers please" check, in places like the MN boundary waters.
Sorry, looks like IL does require registration. The Statutes say a $6 fee. The regs don't require defacing the canoe, or kayak with the numbers though. That explains why I never see them, just the little IL DNR tag. WI requires no such thing. It's voluntary, like hwy trailer registration.