I have yet to play any RPG where wounds were as devastating and consequential as they were in JA1 / JA2. JA3 is probably a close second. XCOM is not even close, because you're not as attached to your soldiers as characters. At least, I'm not.
JA, especially JA2, is the only game that has caused me to wince physically when my mercs get hit, because I'm attached to them and because healing them will take time.
All other RPGs I have played have instant-heal items.
This is why I say it is unique among RPGs when it comes to damage and healing, in my experience.
P.S. I like the fact that mercs get tired and weapons break in the game. It might not be to your taste, but it is not a 'design mistake'. It is an intentional choice.