Thank you for your well reasoned feedback!
There is definitely a lot to think about when it comes to blocking. It is not the first time I hear someone suggest a button for it, but I am very hesitant to go down that route. I've played games where that's how it works, and the tempo tends to be a lot slower than this game. People become very defensive, holding block while warily circling their opponent, looking for an opening.
The overall feeling I'm aiming for is something a lot more fluid. Like this:
It's not perfect right now, but I would rather go in a direction where you're weaving around your opponents, fluidly stepping out of their way and swinging around to take their head off.
Maybe there's a place for a block button in there, but in my vision for what I'm aiming for, blocking is a split-second reaction, not a stance.
To your other points: Rebinding keys is a thing that will happen. :)