what would people be saying if the Secret Service popped that guy's melon with a sniper bullet.. in front of all the tourists. body would sit there for hours with a yellow tarp over it while the press broadcast that image all over the world.. and the "why did you have to shoot that guy" crowd would come out of the woodwork.. or, they were ready to shoot, but there were too many innocents on the OTHER side of the target... this will blow over in a couple days.. had they wounded or killed an innocent, there'd probably be Congressional hearings.
you will give up some security when you balance it with the appearance of bing civilized.
they COULD put razor wire on the fence, but they don't
they COULD build gun towers with searchlights, but they don't
POTUS could cruise around in an (actual) armored vehicle, but they made it look like a Caddy (that can't possibly be a safe as one of those EOD trucks - or Bradley with reactive armor)
the USSS could wear SWAT gear while they're flanking POTUS when he's walking the rope line shaking hands, but they keep their weapons hidden and wear suits.
you know the Secret Service wants to keep POTUS in a box and only let him out for TV.. but they let him get danger close to the public.. all for appearances sake- and this DESPITE Squeaky Fromme, John Hinkley Jr. and whoever actually got a shot off at Ford in SF.
i'm thinking the only publicly visible change to protocol is no more convertibles (see Kennedy)