The main thing that irks me with modern FPS' is that their gameplay mechanics revolve around
limitation, where they used to revolve around
choice.
The game presents you with a situation where there are maybe 2 or 3 solutions to the problem, yet there's always one which is vastly supperior. And as such the game nannies you into playing this way.
Even in games like Half Life 2 there was always a very clear way of doing things. It simply was presented as such.
Now if you play Quake for instance, the maps are more circular in layout.
This means you can play things in a different order, and also the bigger loadout, more creative weapons and higher rate of mobility allow you to tackle situations in a wide variety of ways.
In other words, you have the freedom -- not total freedom! -- to decide both on the micro and macro aspects of the game.
With macro I mean global tactics (non-singular) and micro I mean player to player combat.
In most modern shooters you only have choice in the micro aspects, and even in those there is much less diversity. Because most weapons are rather similar in nature, and there is less mobility -- 1. movement is generally more restrictive, and 2. map layout doesn't allow for easy flanking or backtracking.
Deus Ex is perhaps the best example of a game that allows you to take matters in your own hands. It is this aspect of choice and personal decision making that I lack in modern games.
In a sense you could say that most older FPS games were more liberal in their philosophies, and modern shooters are more collectivist -- you are a cog in the machine. You can rise above the average, but you're always kept on a leash by one limitation or another.
Is that to say older shooters are superior?
No! But, it is
my opinion that they are indeed superior in certain aspects.
Scripted sequences can certainly spice things up, and limitations aren't a bad thing per se. But I think the dominant philosophy has shifted to much to making games like movies, rather than providing you with a set of goals and issues that you, as an individual are left to solve.
For me personally, at the end of the 90's there were Deus Ex and Half Life.
While both were great games, I vastly prefer Deus Ex for it's gameplay mechanics and mix of RTS and FPS. Half Life was an amazing experience, but in the end it was rather on rails. And I've been let down that the industry has moved move in the direction of the latter rather than the former.
Of course there are exceptions, Bulletstorm is very liberal in the micro aspects but hugely restrictive in the macro aspects. Crysis is rather liberal in the macro aspects, and also the player to player combat alows for unique approaches thanks to the suit system. Yet even in Crysis, despite it's strong sandbox aspects, I feel rather confined in my ways of approaching a situation, probably because there's a clear superior way of doing things most of the time. Or perhaps it's just me.
</rant>