I'm giving up my turn to shoot Aliens during their turn! I shouldn't have to worry about how many TUs they decide to burn.
I'm against this method because it inherently preferences defensive over offensive tactics. If I can be sure that my unit on RF will fire on an enemy the moment it appears, then it is
always in my interest to encounter the enemy during the enemy's turn. The enemy will be lower on TU because they will have moved into view and they will probably be closer because they've had to move into my carefully limited field of view. This defensive advantage would be exacerbated by our poor alien AI, which can't really play defensively in this way, doesn't understand indirect fire and loves to rush the closest target.
It would be inherently unbalanced in multiplayer, too.
Heck this explains why my snipers never react. An Alien would have to be dancing in front of them the entire turn before the sniper figures out "Hey I should shoot this guy".
You must keep in mind that a firemode takes into account a series of actions, not just the firing of the weapon as soon as something is spotted. It also entails the time it takes to raise the weapon and sight in the target. If a soldier could just as easily and quickly do this with a sniper rifle as they could with an assault rifle, all soldiers would take them in real life. But scopes reduce situational awareness (hence the range of low-magnification scopes typically used on assault rifles), and sniper rifles are bigger, heavier and take more time to aim unless a sniper has already dialed into the keyhole (something which is not really appropriate for the scale or pace of our battlefields).
Snipers are not reaction fire specialists and shouldn't really be used in that capacity (except on very long range maps from defensive positions). Probably the biggest misconception is that Reaction Fire is Overwatch -- but in UFO:AI we don't yet have any mechanism to properly handle overwatch, in which a soldier prepares himself to fire rapidly on a specific target area. I'd like to see something like this implemented some day, with the ability to spend TUs to increase fire rate and/or accuracy in a small target area in exchange for losing some wider field of view. But it's not here yet.
I also find it silly because the two XCOM games(The first and the remake) just had you set it up and they would fire on the first guy that walked into sight.
Whoa, whoa, whoa! I haven't played the new one, but the old one was definitely
not that simple, especially early on (hence the need for
reactions training). The original had a reaction fire stat and, before it was adequately trained, your soldiers almost never took their shots first. The high reaction fire stat of the aliens was also the source of the
enter-room-die-immediately frustration that was endemic to clearing UFOs.
Reaction Fire is not properly communicated through the UI, which is a real problem I don't want to pretend doesn't exist. But the system is actually not that complicated when you figure it out, and it does reinforce something that I think is a vital part of the 2.5 weapons balance revamp: the most important tactics are squad-based, not soldier-based. You need to use your soldiers in supportive roles to cover for each other's weaknesses. No matter how good a soldier you have, they will be defenseless in some situations. This is a significant improvement over 2.4, where you basically equipped your guys with the best weapons you could and sent them into a shootout with the aliens. It's often the people who were most used to this old style of play who have had the hardest time adjusting to the new style. But in spite of the title of this thread (which will, apparently, never die), I am convinced that the ground combat in 2.5 is more tactically interesting, more intellectually challenging and, therefore,
more fun, than 2.4.