Other state's laws may be dumb to you, but one advantage of registration/titling is that if the state does it right, it makes it easier to track stolen ATVs.
If, for some reason, my ATV gets stolen, the state can find out the VIN without me needing to provide it (or if I don't have that information handy). All I have to do is give them my name. They can look up my information in the state database. And while riding on public land or even when riding illegally on a public road, etc.), law enforcement can see if the ATV is registered (or titled) by looking for the registration sticker. If there is a registration sticker, then they can find out who the owner is and if the rider is the owner. If there is no registration sticker, then that may alert the officer, who can then make the necessary inquiries based on VIN to see if it's been reported stolen.
Having had an ATV stolen back in '92, back before there was registration in Florida, I'm for anything that can make it easier to find a stolen ATV. I fully understand what can happen as far as title issues go (read my previous post), but it's usually not impossible to take care of such issues.
Fortunately, I now have insurance, just in case (I didn't back when mine was stolen). But I still don't mind the registration and/or titling that some states require.
Yes, it can be a pain. No, it's not necessarily dumb.