Here is the original idea for usage based bonuses in Defend teams.
By using usage based criteria you are CONSTANTLY factoring and adjusting for the the meta. Not just “changing it at random” to get mail rewards… unfortunately that would just get people to use the exact same meta team in a pattern.
I’m sure this idea I posted would have drawbacks if implemented. But by encouraging lesser used troops by offering rewards for usage it can’t help but change up a few players teams.