There's been a recent trend with first-person shooters consistently pointing players towards an end goal. In other words, the mission opens with clearly defined objectives, a radar to assist you and, in some cases, an arrow pointing you exactly where you have to go.
The trend began with Medal of Honor, which pioneered the idea of a single-player campaign that had a clearly-defined narrative structure in mind. You had to get to the beach, meet this guy, shoot that tower and so on. Medal of Honor was one of the first first-person shooters, indeed the first mainstream game, to blur the lines between gaming and watching a film.
The experience was more important than gameplay. Sound design and engaging storytelling were used to make Medal of Honor closer to a film experience that you took part in rather than a gaming experience that you had to solve. It worked, of course. Players responded to the immersive experience quickly and, pretty soon, almost all first-person shooters adopted the same formula.
Next was QTEs, or quick-time events. Call of Duty: Modern Warfare was, perhaps, the most popular game to use this. The finale saw the player, fatally wounded, grappling to pick up his gun and shoot down Imran Zakhaev. As a story experience, it absolutely worked. But, instead of defeating an end-game boss, you essentially took part in a cutscene.
Why is this? There's a number of possible reasons for this. For one, an increasing number of players are adults. Adults have responsibilities and less and less time to devote to trying to conquer a boss or find their way out of a level. The story becomes more important than beating the game and, as such, a shortened path to the end is preferable. Moreover, mainstream first-person shooters have to appeal to a wide base of abilities, from the casual player to the more experienced.
Of course, it wasn't always like this. A prime example is GoldenEye on the Nintendo 64. The opening level made no attempt at guiding players on how to open the door to follow the truck into the base. You had to figure that part for yourself. If GoldenEye was released today, there would have been a five-minute tutorial on how to work the doors, follow the trucks and would have given you a dry-run on the whole. No, GoldenEye dumped you right into the action. You either died, got bored or worked out what to do. First-person shooters on the PC like Dark Forces II: Jedi Knight were filled with complex, maze-like levels that, believe it or not, usually deposited you back almost always where you started.
Even when it comes to objectives for each levels, first-person shooters are becoming less and less complex. Again, using GoldenEye as an example, the first level saw you placing a covert modem - which you're not told you have at the start of the level, by the way - somewhere in the base. Again, you're not told exactly where to place the modem. You put it in the wrong place, mission failed. On the rare occasion that first-person shooters have something similar, you're almost always prevented from using that item unless it's at the specific location.
It's not the fault of game designers, however. It's down to players. Players must obviously prefer a more passive experience and keep buying first-person shooters that offer it in record numbers, otherwise designers wouldn't keep doing it - right?