I understand.. There is a tradeoff. Reduced block intervals give more oprhans but increase centralization due to variance. It must be tuned to a better number than 10 minutes. Even 5 minutes has better variance than 10 minutes. There must be a sweet spot.

If someone implements this software for all miners http://www.reddit.com/r/Bitcoin/comments/280gln/bounty_01_btc_for_a_bitcoin_mining_client_capable/ it will force people to solo mine. with 10 minutes we can have 5k solo miners? with 2.5 we can have 20k with 1 minute 50k and so on. It is something to think about and question at least. At which point it centralizes the miners due to orphans I dont know but there should be further analysis of that with respect to current networking technology (which in 10 years the current networking speed might seem like snail mail) and transactions (which is kind of unknown but some analysis with respect to certain upper bounds is an approach to analyse the transactions effect).