I'm going to assume Disney knows more about it's own security needs, construction capabilities, and manpower than you or I and how things will/won't work, as well as the ability/costs of "building properly". If the set-up at Universal would work for Disney, I don't see why they wouldn't implement it. Therefore, I must conclude that there is a valid reason they don't do it that way ("to annoy their guests" is not a valid reason). I have no idea what that reason is, but whatever it is, it's valid enough for them to look for alternate ideas, which they are doing.
Then again, I honestly haven't had any issues with security. Haven't found it to be a nuisance, or to slow us down. Do I think it could be improved? Sure...and clearly, so does Disney.