If there are 2 enemies, each with 1hp and you attack one, they will lunge in with both weapons, kill it with the first hit and just wiff the second. Attacks need to be one at a time. This will be important code later for monks
What is the problem you are solving? Does your proposed change solve the problem? Is your change feasible? What else will be affected by your change? Will your change impact revenue? Does your change align with the goals and strategies of the organizations (Larian, WotC)?
Bonus attack first works, yeah, done it a lot myself. I also agree with OP's point that it shouldn't attack with offhand if the enemy is dead after the mainhand attack.
I've seen this, but with my Rogue-thief I just use my sneak attack first, only attacks with the main hand. I still have both my bonus actions left. Attacking twice with my offhands is my usual go too
