Bag checks are there only to protect DISNEYLAND, not the guest. Comments are above are right that it just makes people feel safer when they really are not.
Anyone can carry a knife in a pocket to Disneyland. No one frisks guests coming into the park.
The bag check is there to prevent explosives going into the park. (which is highly unlikely anyway!)
I think that the bag check should be done away too. It is a waste of time and is not making anyone more secure.