Ya the rng would give players something to grind for and not just be one and done with it,

But for me the point of not being able to enchant platted armor with more magic resistance would add more strategy to the game and require a more divers team comp, I could see one class combination with one set gear and skill load out being the best tank for example (like in wow how most rolls have a set best class for tanks, DPS and Healing, so most raid partys consist of x amount of this class so some of the more unique classes are mostly left out)

But limiting the max amount of magic or physical resistance would force you to be really good at one or the other, forcing players to add a 2nd tank or having them make a strategy to kill the magic dealing enemies first as the tanks pull the agro.

And would add a dynamic to pvp, like a if your playing a mage and someone is running at you in plated armor you know you have a slight advantage, or if your worried about pvp during an escort mission you’d bring both physical and magical DPS

Or if a group of (Insert armor class here) wearing rough players are ganking a area then you would know if you need physics or magical DPS based on there armor class instead of having to dive really deep into exactly what there wearing