My favorite shooter was the first Halo Trilogy. If you wanted to hide you just walked behind an object or wall. You didn’t need to glue yourself to a surface, limiting your movement speed. You could just freely walk out when it was safe. Also, that game was fun because of all the gameplay variety: such as the cool alien weapons and the assortment of vehicle types to use. Both air and land.
The Deus Ex series is fun as well, because it’s not just a shooter, rather all of the stealth and gameplay mechanics are so deep, the game becomes very complex, the shooter aspect takes a back seat and the game becomes fun to master: hacking, jumping high, placing objects and taking alternate routes through vents or punching through walls, disabling electronics, upgrading your powers, using non-lethal means such as stealth kills, smoke bombs and tranquilizers.
Also, and even though you took cover in Mass Effect you had so many class options to choose from, this allowed you to change up the gameplay to whatever suited your style!
So, now that I think about it if a shooter is based entirely just on cover, hide and shoot, it becomes extremely boring. If there is no cool or interesting gameplay factors added in (like vehicles in Halo or stealth and variety of gameplay options in Deus Ex), the game is just bland! Halo and Deus EX are so much fun because of the variety!
At least that’s what I think. To be great a shooter can’t just be a shooter. It needs to have a variety of gameplay options built around the shooting to keep things from getting stale.