(2) The standard Mike Hearn argument: Part of the reason that Bitcoin is viable is that its very comprehensible (at least in broad strokes, if not for the subtle details) to basically any technically minded person, invoking some kind of zero knoweldge thing to _enable_ a specific kind of cheating is far more complex than anything currently in Bitcoin, even if it is a neat idea.
Not thoroughly convinced by this one. You'd be disincluding the mirror neuron ("monkey-see monkey-do") miners; the only aspect they understand to begin with is electricity in -> money out. Maybe that's too crass a simplification, but they may not comprehend a great deal more than that to be tempted. It's so "tempting" that possibly >75% of those purchasing hardware in the past 4 months will never ROI.
I would consider supporting the disallowing of centrally pooled mining in the future, certainly when we get to a stage where the diversity of chain-complete nodes increases along with a block size limit increase/removal. I once read a dev suggesting incorporating the p2pool code into the standard client, I hope that's not been shelved.
Centralised pools were good to to attract miners with deep pockets and shallow motives, they make the uninitiated feel comfortable that they can pick a "winning team", but the manifest effects of that psychology are right now playing out at a new level of ugliness. Maybe the DOS attacks will make people latch on to p2pool more, but the evidence suggests that people are just setting a public p2pool node as a failover instead, and that dynamic is unlikely to win too many converts.
Miners are currently lazy and a very strange type of conservative (they only want to conserve the perceived assuredness of their own income, strengthening the network either doesn't matter or isn't contemplated)