Dries Buytaert

A graph showing user ability over time, highlighting the "suck threshold" and "passion threshold" for skill improvement.
The goal of a software application is to get users up the curve as quickly as possible. People get passionate if you help them kick ass with your product. The "time to stop sucking" and "time to first kick-ass" quotients are among the biggest advantages we have in a world where the competition is both fierce and plentiful. Get your users up there faster, and you win. More importantly, it's a way in which we can make a positive impact on the lives of users. (Taken from Attenuation and the suck threshold.)