Mmmh. Now this seems to me finally a good point. Possibly, because I'm not so expert to find counter-arguments to your one
But as the *instants* you talk about are legit to me, being the game supposed to have high-end late game spells rendering big armies useless (a very nice feature of this game IMO) the problem of the BEs could in fact be a balancing issue - even because the paths you mentioned are surely less popular for late game than the astral, blood and death ones we always hear about.
Someone more expert than me can find a good answer? ^_^