And in general, you ignored the point that "you forget that the Mage's troops are pretty good."
I think neither golems, nor rakshasas, nor gargoyles will die as soon as a half-dead leader reaches them. And even though djinns are weak, their damage is quite good.
Also, if he levels up Light magic, his troops, under buffs, will be no worse than elite orcish troops. And Divine Vengeance will make all sorts of wyverns pay dearly for their "reaching."
P.S. Another trick I'll try in my next game as an Academy mage is Expert Darkness...