Destruction is the weakest form of attack in game...if you maxed 1hand and destruction skill with the related perks, a dagger would do more damage then any expert spell; also the dagger can be upgraded to do more damage then every master spell which is very lame imo.
You can give a small boost to fire destruction damage by using the aspect of terror perk in illusion..dont even bother with staffs at high levels, they'll only tickle ancient dragons
Where are you getting this from? Have you even used destruction?
'tickle' ancient dragons? The expert spells will hit them for ~135 damage (if you choose the weakness spell), ~300 damage dual cast. That's 10 hits you will kill that dragon in on master, from a safe distance, consider how fast you can cast those spells.
The fire storm master spell will half/third a deathlords health on master when perked, that's not weak.
Destruction damage is fine, it's the magicka cost that's the problem. But it seems like you just play a maxed out smithing game and destruction is 'too weak' to use as you can't one hit dragons.