OK. I think it's ridiculous and you don't. If someone really had weapons or whatever other illegal thing/person in their room they'd be hiding them, since they know about the room checks. Or they'd be storing them in their car in the resort parking lot, which, as far as I know, security isn't inspecting the contents of every, or any, car.
As I mentioned, Disney is covering themselves. While I'm sure they hope to deter some illegal things, the main point is to cover themselves from a liability perspective. They are able to say they had eyes on every room in the resort every day, so if/when something occurs, that is their defense. They can't be responsible for people hiding weapons or anything else illegal, but they can choose to enter every room on the property which is about as far as they can reasonably go.
And, btw, I did have a housekeeper come into my room although she didn't make the beds. But that wasn't good enough for them, since the housekeeping staff reports "declined housekeeping" if you don't get the entire room made up. If that hadn't happened to me (and I am not inventing this story--it actually happened) I wouldn't even be reading this thread or thinking about it. Before this occurrence, I was under the impression that having regular housekeeping was the way to not be bothered by security.
I believe you. In one of my earlier posts, I said that a housekeeper simply entering the room isn't enough for them to get a good look around, if they are just dropping off towels or taking out the trash, so it wouldn't suffice for a "check". But the main reason it was likely marked as declined is because they didn't fully service your room. The housekeeping manager-on-duty would not be able to inspect your room for the service the housekeeper is supposed to provide, and the housekeeper would not have performed the duties required in each room when they are servicing it. You did not receive the regular housekeeping service that day, which is why the check occurred. There's nothing erroneous or peculiar about that.
Another poster mentioned instances where they saw a person received a check when they did receive regular housekeeping service. I can speculate a number of reasons that may have occurred, but its not typical and should not happen on a regular basis. So you are correct that receiving regular daily housekeeping should preclude you from receiving a second security check during the day. But on the day you described, you did not receive the regular housekeeping service so its a moot point.
Furthermore, if Disney really wanted to make sure that no one had a weapon--although there seems to be a dispute about whether these room checks are for weapons or for checking to make sure human traffickers aren't using Disney for their activities--they'd have a metal detector you'd have to pass through every time you came into the resort. Of course, they don't want this, since it'd be upsetting to guests. They're willing to go only so far.
Again, the checks are not for one specific reason. It can be to deter anything - even things not illegal. Suicides and medical emergencies also happen in hotel rooms. People trash and vandalize hotel rooms. Getting eyes on each room every day may help in these cases too.
Metal detectors at hotels and resorts are not industry norm, and there would be no way to police that when they have multiple points of entry at every resort and parking lots right outside resort doors. That is not a viable option. The best they can do is metal detectors at park entrances, which they have.
Also, it'd be very easy for WDW to keep track of every guest, no matter how full or empty their resorts are. They know where you are and what you're doing.
They DO do that already. But they are not doing it to profile guests and flag certain ones as suspicious so they know who's room to enter that day. Again, that would defeat the point anyway when the point is to get a CM in every room every day for liability purposes. Remember, Disney is private property so they carry a burden of some liability for what happens there. The checks are a form of protecting themselves, something MANY hotels and resorts implemented after the Vegas shootings (see also: Starwood/Marriott and Universal resorts).