Why are they so hard to do well in JA? They work pretty well in any counter-strike. Yeah yeah this is isn't cs blah blah, but you get what I mean.
Because CS:S runs on a much better engine, and CS:GO runs on that same engine, but it's being constantly upgraded to fix bugs by a highly proficient team of people, along with a technical team that is staffed by dozens(if not more) of highly professional people.
IDTECH 3 stopped being worked on as soon as IDTECH 4 came out. IDTECH 3 isn't built to handle that, and to make it handle that stuff without implementing some crappy half-assed smoke effect that kills FPS(as the engine is meant for older computers, even high ends lag when playing this), they'd have to go in and mess with the engine itself, or move it to a new engine, and currently the dev team is understaffed by people with very little time on their hands to do this, so naturally it'd take a fuck of a long time.
That's not even mentioning dev and community attempts at putting this in the game. There have been attempts to make smoke grenades in the game, mostly in custom FA maps. It either is a crappy grenade that doesn't do anything except make a vague smoke screen that's easy to see through, or it makes a giant vape cloud that never goes away, ever.
It's just been done to death, as I've said before. That, and nobody really wants it anyways, and the only people that do are people who are unacquainted with the mechanics of the game, specifically the team play aspect.
That's not even going into how there's a time limit on round, and slowing down the gameplay to a halt with a smoke grenade is only going to make more timewins than anything, but that's only between gunners. A smoke grenade would only hinder both sides if it was thrown. Sith/Jedi on both sides would just run through it and kill the gunners on the other side, quickly devolving the game into a round of 'which team has the better duelists/more Jedi/Sith'.
It has just been done to death at this point. There is
NO POINT WHATSOEVER in inserting this useless mechanic into an otherwise feature packed game. End of story. I suppose if you really want it so bad, you could create a new smoke particle effect from scratch, that's compatible with IDTECH 3, and then you could go make your own FA map, with it's own classes, then modify a conc nade to produce the effect for however long you make the effect show up for.