I completely agree with you Chakk88. Mixing damage types means you have to eat through 2 armor types, and since Magic is performing poorly this patch it means all-Physical parties are quite strong by comparison.

I'm not sure if an armor degeneration scheme is necessary, I think magic damage just needs a buff across the board.

@LaughingLeader
While some enemies have Magical weakness, the vast majority do not and even when they do it is often pretty minor. In the current content there are far far more cases of enemies with multiple large resistances, immunities, and some even have resistances to all elements. For the most part, Magic Damage is at a reduction, sometimes small and sometimes large.

This is in addition to the fact that Physical damage users are spitting out far more damage than what Magic users are doing. Wands have the absolute lowest damage per AP by a large margin and Staves are beat out by Str weapons by reasonable amount. Even spells have low damage when compared to weapon abilities.
Another large hit to using Magic is that they lack a solid passive skill to increase their damage.
Weapon-based skill trees can stack points into their weapon, which buffs all auto-attacks and ability damage by a solid 5% per point (this is multiplicative with the stat increase).
Magic users on the other hand have no equivalent. They can do Aerothurge, which only adds an increase while the enemy still has armor. They can go Pyrokinetics, but this will only buff fire spells. They can go Dual Wielding or Two-Handed but this will only buff damage from the Wands/Stave, respectively. They can go Huntsman to buff all damage, but only when you can get a height advantage. There's no reliable equivalent.

This is the problem with Magic in practice

In theory, there could be more enemies with large weaknesses.
There could be enemies with significant Physical armor with low/no Magic Armor. (this mostly already exists)
However, without a buff to put Magic damage on-par with Physical, it's a tough sell. It's just a lot simpler to have the whole party doing larger amounts of physical damage than to worry about breaking through armors a lot of the time.

I'm not saying Mages can't do fine in the game, I'm just saying they often feel weak when compared to Physical.