Your point is well taken but my opinion is the advent of e-tkts has made the enforcement of checking tickets at security a much more hit/miss proposition. Personal experience -- we rarely check bags and have absolutely nothing that says we're booked on anything. We will typically just head for an RCC and check-in there.

You are correct that this is a "hole" in security but can you imagine getting off a plane and NOT having to wade through 200+ people greeting the 100+ people coming off the plane?