That's the thing I don't like about most TV / movies. All the police forces / enemy forces / allied forces are portrayed as incompetant boobs who couldn't hit the broadside of a barn.
Reality is that most forces are reasonable to well trained and would put somebody down.
At least in "24" they portrayed their forces to be pretty decent in a combat situation.
Even in "Enterprise" the MACO's didn't drop like flies. The sheer number of MACO's that died are very few, even the extras got some real fight time that made them look competant.
My main issue is with Hollywood and making badguys / goodguys look like fools to make the other side look good. Everybody should be following the "24" mentality where both sides are competant and show them to use brains when approaching a situation.
I know it's a little bit difficult to ask, but make both sides intelligent for once. -_-
Thing is, a lot of the timeit simply slows the plot down too much if everyone on the show is intelligent. So for the sake of the plot, all bad guys, or at the very least anyone who isn't a main character has to be overwhelmingly incompetant. The audience wants entertainment, not realism. Realism is boring.
The main reason the MACOs were shows to be competant was because that was their purpose, they were meant to be the ultimate unbeatable ass kicking squad.
But they are not called Starfleet Marines. They are a part of the already existing Starfleet Security division. Starfleet is the Federations defense agency, and if Starfleet personnel are defending a colony against a Klingon attack or holding a communications array from the Dominion, then they are a part of Starfleets combat division, known as Starfleet Security (providing Security, one dead Jem'Hadar at a time).
Well, those guys had coloured stripes on their uniforms indicating they were't all security. There were command and science officers mixed in as well. Logically, since these were combat situations everyone was required to get into combat gear fight the enemy, regardless of their specialities. Just like in the actual military.