Lol who here is playing a Doom game to be surprised, the Doom games really are as simple as shoot anything that isn't you and frankly none of the Doom games had the shocking surprise element of oh my god I have to fight something here. While the early games had the advantage of pre spawned enemies encountering them was hardly a shocker, you teleported or opened a new door it was a bet that you would be fighting something the advantage the new Doom has is that you areYou're killing monsters that are in actual physical locations. You're not wandering into a conveniently placed combat arena so enemies can suddenly spawn in. In the third person shooter genre, a common design mistake is to have corridors connecting open areas with a bunch of conspicuous waist-high walls that scream "Wow, there'll be a 'surprise' ambush here! Just like the other 30 'surprise' ambushes so far!"
a). Forced to fight, in Doom 1 and 2 you could run through a level and fight nothing
b). You are forced to fight the enemies in a fast paced always on pace, instead of having the option of falling back or looking for bottlenecks to run herds of enemies in to. It works and it works well
On top of all this the more linear design means that the pace is constantly kept up were as previous Doom games suffered from examples of the gun play being utterly stalled while the player went looking for the next keycard or backtracked levels to find something they missed.
I have always played the Doom games to just shoot stuff, quick and simple gameplay, Doom 4 nails it while removing the bullshit that actually made the old Doom games a pain to play at times.