I dont understand these nerfs either.
My Snipers are the last line of defense at a certain point in the game. Nerfing them because they are used too often statistically seems for me exactly the wrong way.
The question is, why no other soldiers/tactics are used in the game?
For me its because I just lose my soldiers all the time if come to near to any kind of foe with any soldier.
So the solution are snipers to stay alive.
Even an Armadillo doesn’t stand more than 2 rounds against the usual Arthon waves. And it have an useless firepower and a costly trade of 3 soldiers(snipers e.g.) less.
All possibility (known to me currently) to get through the armors in the later game (beside the snipres) need a Heavy nearby to hit something and lower the armor. What usually isnt neccessary anymore since the Heavies are donig well damage if pierce the armor. But dying if they miss or 2 other enemies are nearby.
So psychic attacks were an good alternate. But nerfed now.
And the other ways … like sneaking behind and shocking them is very risky… and dont kill them afterwards anyway.
Pushing through with explosives is very costly for your resources after a while.
Assault soldiers are pointless anyway (nerfed or not) since they are always need to be too close to hit and suffer from return fire.
Poison, Virus, Acid… sounds good. But you need to place about 60 loads and survive for 3 rounds after that.
So no matter which faction I focus on, on a certain point they are only snipers left to stand against the waves. Like ~20 Armored-Arthons
And I dont even want to start to analyse the Sirens … just so much:
One Siren in one Round jumping from a roof. Mindcontrol one Soldier and kill two others with melee.
…what shall I say… hmm… it was the second round in the mission… how could I avoid that?
OK… lets be more constructive.
How a about making the soldiers more endurable?
With better armor or more health without losing too much aim. Squishy/No Aim = useless = dead.
How about adding strategic possibilities for distract or defence?
Full cover, Smoke grenades, Flash grenades, Pheromone decoys, head dmg disable aim or recognition, distracting sonic sounds/taunt, cover fire.
Improve stealth soldiers? Choose Mission placement of stealth soldiers?
It would be helpful to see how the chances are to being discovered if in stealth mode.
Pre mission abilities of aircraft.
Area scan, airstrike, covering fire, drop spike mines defense
And so on…Still have any ideas, but I dont know if I have a different vision of the game ? 
P.S.:
Sorry for not being very detailed. As a Gamedeveloper I see several points to talk about. But I prefer to point at some points to look at instead of being detailed.