Having counters does not equal being balanced.
Most of these characters can be beaten, and have counters.
But guess what? Since they are the best available option, nobody will pick other characters because it's not worth the trouble.
The current meta is get Rex as your leader and throw in any powerful character you have. Bam, top 10 worthy team.
This is wrong, and until people realize that these few characters smother the entire PvP experience, things will not change.
People here are afraid of nerfs for some reason, but a competitive game with no nerfing mechanism to keep strong characters in check is doomed to be either imbalanced or crippled by power creep. This game manages to be both.
@OP, it's pretty much worthless to even evoke game balance here. 80% of the playerbase thinks the game is fine currently, despite its blatant lack of variety.
Most people will stop at "nerf", will look at their team and realize they may lose power, so they decide to dismiss your claims with simple, dumb arguments such as "duh, you're crying on the forum! Git gud!"
Most people here have no game balance understanding, and are not able to understand game health on the long run.
Heck, one of the game balance specialist posted not long ago that he used an Arena team made of Wiggs, STHan, Lando and Boba.
So I guess even their balance team itself has little idea when it comes to game balance.