No one here is giving you a good excuse to buy a K20.
I used to make tons of 8x10s and the occasional 11x14 from a 3mp point and shoot. The walls of my local photo store are covered with 11x14s from cameras with half the effective resolution of a K10d kit. Sometimes I think we do get a bit obsessive with resolution and forget, as pointed out above, that larger photos are viewed from a distance.
It reminds me of my film days when I would always have one body loaded with K25. Unless a friend put his nose up against a 16x20 Ciba, he would not notice the difference.