Some of this may reflect my lack of familiarity with SR. But some of it is the randomness inherent in spell choices. Gethras, for instance, is 14th level. Here's what he ought to get for defenses:
Combat protections: Mantle, Stoneskin, Mirror Image x2
Spell protections: Minor Globe, 2/3 chance of Spell Deflection or Spell Turning, Shadow Door
Triggers: 50% chance of a defensive Minor Sequencer (MI + blur or similar), 2/3 chance of a defensive Spell Sequencer (many possibilities)
Contingency: Stoneskin, or Minor Globe, or Improved Invisibility, or Minor Spell Deflection
If that random list breaks all one way, it could end up having relatively little antimagic protection.
It is in general a balancing act to work out how much and what defensive magic wizards should have: too little and they're killed easily, too much and they sit around endlessly defending themselves without doing any real damage.
As for area effect spells: Bartimaeus is right that the problem is mostly self-immolation. SCS is a bit more gung-ho about this in v32 and later, but still quite cautious - for me, nothing violates believability more than a wizard using area effect to kill their own forces and themselves (something that happens quite a lot in the vanilla-game AI). I'm surprised you're seeing quite so little of it, though - solo invokers, in particular, ought to be using minor globe and then fireball/lightning bolt quite a bit.