Getting rid of their Antimagic Susceptibility makes all the Animated Objects a whole lot less interesting. I can understand Wizard wanted to get rid of "traps" for newer players, as casting a third level spell for a single CR 1 creature is in most circumstances a waste, but I would've preferred they kept it and instead added more threatening Animated Objects. Making it so you can teach players early about that Trait, and reintroduce it later in a more beneficial environment for them to use.

Also, getting rid of their False Appearance makes them less interesting once more. In this case they wanted to get rid of Traits that don't directly interact with game mechanics; but it does interact with Stealth and Surprise. The wording could've instead been changed to something like: "False Appearance. The Animated Armor automatically succeeds on Stealth checks while not moving."

I doubt it was because the mechanic didn't interact directly with game mechanics, and more the trait was taking up too many words they needed, and they figured the DM didn't need to be told an animated armor can disguise itself as a normal armor considering how iconic that is. Besides, the mechanics they started giving the False Appearance trait (advantage in initiative if it is motionless at the start of combat) have been made redundant with the new Surprise rules.

I am annoyed at the loss of the Antimagic Susceptibility trait though, but I think they wanted to remove the expectation from players that Dispel Magic works on things other than spells, or at least should work in contructs at large like golems. I half wish it did, but oh well.

Going through all the monsters in alphabetical order this is the first one i prefer the old artwork.

Can only agree to the previous comments. I dont like that it isnt affected by anti magic anymore. For the false appearance i will just rule as dm that i can appear as normal armor. 

Overall the first monster i have nothing positive to say