I actually find that ethereal us a dish best served in small portions. Arcane zap, priests holy pimp hand, jet stream, invisible fist, etc.
With very few exceptions incorporeal things tend to have very low life totals, and the big ethereal hitters are expensive and under powered. Id rather stick a jet stream on a wand with a hawkeye and remove the threat with a few small strikes than try and gamble on my 6 dice 4 sp 9 mana force hammer doing that crucial, statistically improbable 7 damage in one shot.
Incorporeal actually lowers the damage taken by more than a 3rd if you think about it, because i limits takable damage to the lowest possible value. Resilient creatures can at least be killed with one solid crit role as 3 dice can do a max 6 damage. 3 dice can do a max 3 damage with a perfect roll to an incorporeal object. That just sucks.