Wilco86 said:
I played System Shock for the first time a couple of years ago (SS Portable to be exact), and I was shocked how rich it is despite all of its clunkiness. Sometimes background monitors showed door codes instead of just mentioning it in datalog, sometimes I was searching for a certain corpse with the help from a image of an unique face from a log to find an important item I needed to proceed, multiple different minigames to bypass locks, etc....
Many say that modern games are being dumbed down and that might be exaggerating, but I do wonder why - now that we have the technology and processing power - complex and mechanically rich games like System Shock are so few and far between. (If System Shock played like old Thief games with leaning and crouching, it would be almost perfect.)
There is leaning and crouching in System Shock 1 (and 2, not surprising since 2 is made in the same engine as Thief 1 and 2). You can peek around corners which allows you to survey an area before moving into it. Crouching serves more as a navigational function. The game doesn't strictly have stealth features though, so your not going to ghost your way around the station.
System Shock 2 had a more functional stealth system though it's more suited to avoid specific encounters, not for ghosting entire areas... also the last few areas of the game become a bit of brawl, so you shouldn't neglect offensive weaponry. If you invest in PSI you can also get an invisibility "spell" that could make those late game areas a lot easier, but your going to want to have some skill with the pistol at least (I love my Wrench and Pistol playthroughs... very tense).
As for your question... unfortunately complex systems aren't easy to market. As a general rule of thumb, the more things the player is forced to concern themselves over the fewer players there will be to enjoy it. On the flip side, complexity can easily slip into contrivance if not handled well.
As far as major AAA games are concerned Deus Ex Human Revolution is about as complex as they will get... but if you are willing to explore other areas of the industry you can find games like EYE: Divine Cybermancy (which is imperfect and often convoluted, but worth a glance). The recent Alien Isolation, if you can stand a slow paced horror game, has a very strong System Shock feel to it too, at least atmospherically.