Agree, but have to calculate subtraction for value of IE6 user. IF 10% - 15% of traffic, WHAT percentage of orders and what percentage of dollars?
Perhaps a bit unseemly to compare trailer parks to exclusive gated communities, but there is a correlation between up-to-date and savvy - and not. Split the difference and call it 12% of traffic. What if that is 6% of sales. I can get a 6% increase in sales by taking even better care of my more desirable users.
The more the question comes up, the more likely it is already answered. The upswing in "Should I support IE5.5 and NN." helped to establish that answer was no. When everybody is asking, the tipping point has probably been crossed for most.