I agree with most of that. One of the things that never made sense to me about X:EU was how limited your resources were. You're literally the world's last hope. Your income should be in the billions or even trillions, but instead it's in the thousands. The U.S. Military alone has vastly more resources than the fictional XCOM project, which is supposed to be the culmination of the whole world's resources on a last-ditch effort to defeat an alien invasion. The fact that you have to worry about money at all is a little silly, from an immersion standpoint.
The XCOM 2 plot makes a lot more sense, given that in this game every nation has allied with the aliens, forging a "peace agreement", and you are instead a small group of ragtag resistance fighters, using the limited personal resources of rebellious sects. It makes perfect sense that you have no money, you're literally fighting against the world and the aliens now, instead of just the aliens. So it's more immersive in terms of the plot, and it's more immersive in terms of the way the soldiers act and behave. Anyway, a 5% chance to instantly kill an opponent (which is what the weapon mod does) is so hilariously unreliable that it's barely worth mentioning. It's just a nice thing to have every once in awhile when you get lucky.