Combining magical and physical armor into one is TOO much of a simplification. The larger problem is that mixed magical/physical teams are discouraged because they have zero synergy. Keep both armors, but split the damage so that Physical attacks do, 67-75% of their damage to Physical Armor, and 33-25% of their damage to Magical Armor. Magical attacks are the reverse (67-75% to Magical, 33-25% to Physical). This allows for better synergy between mixed teams.
If one type of armor is gone but the other is still up, damage from the opposing type can seep through to Vitality at the same rate.
So a Magic attack which does 100 damage and inflicts a CC, hitting an enemy which has 500 health, 0 Physical armor, and 300 Magical Armor. The spell will do 75 damage to the Magical armor, and 25 damage to health. The CC is blocked because magic armor remains. The enemy now has 475 HP and 225 Magical armor.
A Physical attack does 100 damage and inflicts Bleed hitting that enemy will do 75 damage to vitality and inflict Bleed (no Physical Armor to block it), and 25 damage to Magic armor, reducing it to 200.
Obviously once both armors are gone all damage goes to health and statuses will land.
The only logical choice here is adding CC resistance chance to both amour.
You have 100% amour on? good, you're immune to any first CC spell casted on you. After that your chance go down gradually as enemy attack/throw spells at you.
You're adding random chance back in, which is the exact thing armor was added to remove.
It isn't much different than current system
False. It's totally different than the current system. Because you're adding random chance back in.