It is true that not many games written in the 80's and early 90's remain in production with the same execution of mechanics they had back then. And indeed, some systems — like Millennium's End, Phoenix Command, and others — that tried to shoot for extremely crunchy, simulationistic systems, have since then gone the way of the dodo; simply due to being much too complicated to be practical at the table.
But as I just posted on another thread: like all other technology, mechanics of RPG's have evolved over the past three or four decades. What could be considered okay in 1990 would in most cases be considered subpar today. That goes for everything from mechanics to pure production values.
The question currently at hand is however, is the current trend towards lightweight, crunch-free systems truly universal, or is there a fair bunch of people who look for TTRPG systems that can scratch a similar level of crunch-itch as the old T2k editions did back in the day — only with more modern solutions for the mechanics?
For my own part, I subscribe to the latter — and I'd be inclined to say that this is borne out by that there are still many fairly crunchy systems around, have loyal fan bases, run successful Kickstarters, and get played a fair bit, to all appearances. Call of Cthulhu, Harnmaster, Chivalry & Sorcery, Pendragon, Western, Traveller5, Shadowrun ... just to name a handful. New ones also crop up ... some of the new euro games are fairly crunchy, too.
My point is that detail, resolution, crunch ... do not necessarily go hand-in-hand with complicated and cumbersome resolution mechanics. If you accept that not all weapons will have identical stats, and that you need to jot down the specific stats of (or hold the specific cards for) each weapon you have anyway, a whole lot of complexity can be hidden away behind each number.
To reiterate something else that I wrote somewhere a while ago — in the end, it's all about flavour and atmosphere.
Providing these is to my mind the whole point of even having a game system in the first place.
In the real world, it makes a very real difference if I try to hit someone at 700m with an M4 or an M16A2. And so, I need the game mechanics to show me that difference; to make it matter if I have one or the other.
To me, Twilight:2000 is, in the end, a mainly military setting, and small-unit tactics should occasionally be part of it. Not all the time, perhaps not even very often, but definitely now and then.
And when it does — as the strengths and limitations of whatever weapons I have available to me will inform my tactical choices in the real world, I want the weapon properties in the game to inform my tactical choices there. With mostly recognisably similar results, N.B.!
Because it it doesn't matter — why have any stats at all? Why bother with having the game mechanics there in the first place?
Why not just sit around and improv group-story tell freely, and dispense with all the faffing around with character generation and dice-rolling altogether, if they don't help us distinguish which choices matter and which don't?
Ultimately, I feel that making a T2k game with a crunchiness level akin to Alien — where weapons ranges are abstract narrative zones and ammo lasts forever until you fail a dice roll — would be a mistake of epic proportions. Fortunately however, we already know that isn't the direction this development is headed; rather the opposite.