To put it succinctly, no, it doesn't need to be revised. There is nothing wrong with your need for symmetry, but its lack is not a flaw. If you don't like it the house rule it, but the consensus is that it's not a problem.
You have misunderstood some arguments though. The primary one I see is that you are seeing "enemies die quickly" as "enemies are weak." That is not what I was saying at all. Look at it this way. Enemies are already asymmetrical with heroes. They don't have all three attributes, for one, nor do they have rules for encumbrance or healing. They do not even track damage the same way. None of this is because "they are weaker" but rather that they only have what they need to fulfill their function. And that function is to be a challenge to the players and nothing more. IF they persisted between combats then some of your concerns would be more valid (logically, not emotionally, see the first paragraph) but even that can be dealt with easily with gm handwaving.
What is apparent to me is that you seem uncomfortable making the rules your own and generally being a gm. Not calling you out, I just get the sense that you are newer to it. We've all been there. It's cool. The players should never know when the bad guys are using their resources or even what resources they have. That is the purpose of the screen. They don't see what happens behind it because they don't need to. And if I'm wrong on your newness then I apologize and can only say we have vastly different ideas on gming, which is also fine, I just don't have any advice to give.
“It is useless to meet revenge with revenge; it will heal nothing.” - Frodo Baggins, Return of the King