I think it's a mistake to assume that, if you breeze past security, it means that it is lax....most of the general public is not an actual threat. Inconsistency (across the parks or on a daily basis) serves as a deterrent to an attacker's ability to adapt their tactics to any perceived vulnerabilities. To a certain extent, bag checks are perfunctory (aka theatre), but again it serves a deterrent function. While it may seem that security is not effective at a tactical level, keep in mind that it may be serving a larger strategic purpose.
The changes that WDW has implemented appears to be consistent with risk mitigation according to current counterterrorism threat assessments for soft targets, an ongoing process....certainly they work closely with local government and law enforcement, and this set-up probably gives them more flexibility to change security as needed (as the risk at any given moment is small but fluctuates with intel). Regardless, they always have to strike a balance between effective measures and public accessibility/ willingness to comply, and largely without the public being aware of any given specific threat.