This is a feature, not a bug. XCOM has always been punishing (did you ever play the original?). Loss of team members is part and parcel of what makes the game. If you don't like it you can always play on lower difficulties and turn off ironman. But accepting that you need a stable of red shirts as well as not trying to get too attached to your heroes (especially the ones you name after family members) is the XCOM experience.
I did and I understand that, I've completed 2013 on Ironman Classic (Too lazy for Impossible since it requires nearly perfect strategy and I'm not that good) and the original. I'm well acquainted with the "that's XCOM baby!" moments.
My issue is that there's no real option for a plan-b in terms of soldier loss. On higher and even medium difficulties in XCOM2 by the mid-game you're at the point where
there are skills which you cannot afford to give up. Salvo and Volatile Mix immediately come to mind. The Guerrilla Tactics school only mitigates this, but doesn't erase it.
It makes training B-Listers outright suicidal rather than challenging, since the whole game is based around volume of fire. Bringing redshirts along means endangering your good soldiers.
And before you accuse me of the overwatch camping strategy, I would like to say that I played
very fast and loose with my team. My whole beef with XCOM 2 isn't the timers alone, or the abundance of tanky enemies, but the fact that those two are
combined.
Don't get me wrong either, there's a few things I really liked about the game, so I didn't despise all of it. I really enjoyed the expansive customization options (though Anarchy's Children stuff is an eyesore), and the Overwatch/Sniper nerf was well thought out (even though Gunslinger outclasses it in every way). And there are fun moments, like launching acid bombs out of concealment and devastating an enemy squad, or using the gunslinger to mow down low-level enemies. But all of it doesn't make up for what I feel was a core gameplay mistake, which was slapping on timers and health to the enemies. Besides, it's not like the XCOM team couldn't have gotten creative with the enemies either, look at the Andromedon for example, or the Viper. They both combine interesting abilities and fit very nicely with the new game mechanics while not being overpowered.
They could've easily done something like, say, have an ever-increasing and more powerful number of enemies drop in after breaking concealment, or done a lot more with the concealment phase like letting the player complete missions by stealth alone. (especially when ranger/scouting is encouraged) Imagine being able to distract the map enemies while the ranger retrieves a VIP, or using the gremlin to hack a console from concealment. It would've fit and added another layer of strategy on top of the game.