This got me thinking. In breakthrough, the two viable classes appear to be engineer and recon. As a defender, with unlimited tickets, there isn't much of an incentive to wait for a revive unless you are trying to take a point back from the enemy. With the introduction of armor in this mode, or the unbalanced changes recently made, the solution appears to be an overwhelmingly number of engineers. Just wait for players to start calling for more tanks or a nerf to engineers because the initial response was to overwhelm the additional armor with more engineers.
The assault class only has one redeeming quality and that is the spawn beacon. In the breakthrough game mode the other gadgets do not have as much utility as an engineer or recon does. I am convinced that if they gave the spawn beacon back to recon the assault class would have no utility at all.
The reason I say that recon is necessary is the potential for setting traps and detecting when the attacking force has gathered in large numbers on one side of the map or the other. They can engage at long, but limited distance to support the defenders who are fighting up front. Also, the drawbacks of using a sniper rifle without a recon class outweighs the performance of any other weapon platform for this map mode. The separation of class and weapon types no longer incentivizes players to play a class to level the class weapons. Essentially, you can level any weapon you like using any class you like. Revives can be done by any squad mate, albeit a little longer and the short life expectancy of the players incentivizes a give up/respawn meta.
Decoupling the weapons from classes and specific gadgets for classes appear to incentivize a more singular, solo play style.
From my experience within the breakthrough game mode the engineer appears to be the most useful because they can engage armored targets quickly and effectively but they can also engage infantry just like the rest of the other classes.
To make this game mode and all other game modes great again, the classes should find a balanced approach and an identity for their intended playstyle. Dice should have incentivized roles over individual players.
TL;DR: Dice designed it this way and mistakenly made it worse by trying to balance it.