It sounds funny but I wonder how big of a change that would really be, alone.
Mid-fight, you'll have to pay more attention to AOE spells (mass disease? or the marksman lvl 15 AOE spell?), but usually I start the fight with all the AOE, simply because I kill everything in one round usually (and thus your change wouldn't change anything).
I think it would go hand in hand with a buff in health to ennemies, but it could change alot so I think it needs testing first.
And if you change friendly-fire, you could give it to ennemies too because that wouldn't change much for them: they mostly don't use AOE abilities except for grenades which already are damaging to everybody.
For ricochet to be less obnoxious in a friendly-fire setting, you need to know how it works and if you can control the angle (I think there's no angle, it just selects targets available in a 7 meters radius, no matter the impact direction).
