I'll be honest, we leave our stuff unattended at WDW all the time, partly because of the false sense of security you mentioned. However, reality is that the stuff we leave unattended is of very little value. While we'd be annoyed if it got stolen, it wouldn't ruin our trip. For example, we bring all of our own food into WDW, we don't eat at the restaurants. So with a family of 5, a full dinner is quite a large bag. Our soft sided cooler is a monster. We stick it in an umbrella stroller so that we don't have to carry it. We often leave it in stroller parking for hours while we hit the rides, then come back for lunch or dinner. Sometimes we'll leave our gear bag too, if we don't need it. It usually contains some of the $1
WalMart rain ponchos, sunscreen, and maybe our kids autograph books (they like them, but they aren't worldly possessions). If someone really wants our $15 umbrella stroller that's now 5 years old...have at it. Want our dinner? Hope you like what we packed. It's a risk we take, and in 10 years of doing it this way, have yet to get burned...even once. But if it ever happens we won't complain much. $50 later and we're back in business.