I'd be willing to help test this system. It doesn't seem to account for ranged attacks, attacks where the defender has no chance to block or dodge (such as surprise attacks), or simultaneous or temporally close attacks (pretty much two on one conflicts). The last one there isn't avoided by having one-on-one fights, as delayed ranged attacks and physical situations (such as from midair, hitting an enemy down as he collides with the ground) can still synchronize attacks. For ranged attacks, I say that ranged attacks are weaker in some regards, while their main benefit is avoiding counterattacks from failed attacks (your opponent is at a distance, and they can't reach you (unless they designed some sort of rubber-rubber fruit)). For the lack of block or dodge, I'd say that they automatically have some small limit to their roll based on their condition; healthy, sorta armored enemies could be forced to 5 max, while the especially prone are auto-1. On the topic of my example, reaction time may play a role in unforeseen attacks, and could be part of the roll limit; essentially, if they are not prepared for the attack well enough beforehand, they get the roll limit. This could add a mental layer to strategizing and design. Anyway, third point, sorta covered by the second solution. The defender would have to split their focus/effort(/preparedness) between the attacks, whether they could choose how it's split or not. With enough reflexes, it could be logical for a defender to be able to block each of two attacks with their full force..provided they block the first one well enough.
But you want playtesters, don't you? 3 strength, 1 Dexterity.