Well, if you think about it, you can have all the high-tech widgets and geegaws and whatchamacallits and bobamagnihts you want, but mechanical simplicity will always win out in terms of reliability and ease of maintenance/repair. The grenade launchers in aliens were Remington 870s (hilarious note: depressing the nosecap of an M40 grenade can supposedly cause it to go off. However, _FOUR_ of them are supposed to be able to be loaded into the TUBULAR magazine of an M41A's underslung grenade launcheR) and Hicks' shotgun was just a personal weapon.
Of course, in games like Half-Life 2 (SPAS-12), I wish someone would lean over and tap Gordon Freeman on the shoulder and point him toward the switch/button/lever that flips the gun to Semi-Auto mode.
All that said, I don't think mechanically simple firearms will ever really be out of style until you can make electronics as or more tough than just plain ol' metal-touchin'-metal.
"10mm explosive-tip caseless. Why?" ~Lt. Gormann
~Slam_Fire
PS ~ In games, especially, if shotguns didn't have the sort of delay caused by the pump-action, they'd have to be drastically weakened to maintain weapon balance, and that'd be even less cool.