That's where, as many have pointed out, it's all in your (collectively) head(s).
The unobtrusive measures are far more effective than metal detectors. It isn't making anyone safer, sure it may make the uninformed *feel* better, but it doesn't actually do anything to stop those intent on attacking. Which is, allegedly, why the detectors went in.
The areas to attack, such as bag check near rope drop, the lines to the monorail, on the ferry ect ect can't have anything done about them. The number of employees and vendors coming and going... the number of areas someone could easily chuck a duffle bag filled with weapons/explosives over the fence and a group of bad guys could scoop them up after entering the park... or just hop the fence and then start shooting in the back of fantasy land for just one example. The fences only make it so honest people don't skip the turnstyles and anyone planning on mass murdering isn't going to care about getting a trespassing warning.
Carbon fiber knifes (cheap readily available) won't be picked up by metal detectors, have a couple guys go into DHS and ride in 3 different cars at the same tie in Star Tours, everyone belted in and one guy going down the rows from behind stabbing everyone in the neck.... Same time one guy goes into the HM preshow.... Getting fixated on firearms is only one aspect of this.
Honestly, this "safe" and "safety" stuff is pure nonsense. Securing an aircraft is something that is something that can be done fairly well. There are ways to defeat the security but it's much more difficult. Themeparks? Get real. Think about, the TSA fails at detecting weapons 96% of the time. As we've said, it's all in your collective heads. Safety and security are an illusion. Nothing more.
*****BTW I got sent through the metal detector today. 30 seconds of park time wasted.... for something that made no one any safer. The Wizard of Oz would be envious. Smoke and mirrors.