I did a post about why was this stuff so common trying to get the moderators, or someone on development to give insight. Didn't get that, but got alot of support for this to stop. So, I've decided to explain why this an awful idea for the game.
Starting off, it's allow you guys to get lazy with your monsters. For instead of building interesting movesets, and having a trait to either expand, or balance potential. You've got unbalanced messes that are busted because everything has to have a resistance trait. Frostbite would have been busted when he initially came out, and you guys knew this so you gave him an awful trait. However this memo is just gone now for the I'm guessing sake of people trying to see the monster as more appealing.
Finally to the bigger issue, how this has, and will continue ruining the meta. When you guys changed traits to unify effects (Except Burn), and balance deniers by preventing chain deny (Except Possession). It showed massive hypocritisy within this apparent care for "improving" the meta. For you guys change this, but still aren't considering how hardened, and tough aren't ruining the meta right now. This hardened, and tough trend has ruined war, and PvP (To a Lesser Extent) for me. For guess what, I'm having to deal with every war 1 through 3 hardened monsters on every defense team. Guess what that means, a gamble that I deny them. Guess what that isn't, strategy, this is just luck. Not at all enjoyable to deal with, and this will eventually lead me to quitting the game. Luck isn't at all enjoyable to rely on at all, and doesn't allow for fun defense teams to be made. Everything having hardened, and tough causes not just stagnation, but also hurts everyone playing the game.