Unless you keep the app open all the time (I’m assuming you do that because you have the focus of a guided missile), this is a program that you open and close several times a day. So why, oh why, does it take so much time to load?
This is why, even though I disagree with many of the things Apple is doing with the OS, I think Apple is on the right track with the app lifecycle model with Lion. Most computers ship with far more memory than people actually use these days; why should you constantly open and close apps when you can just leave them resident?
Most of the reason people even bother closing apps anymore has less to do with the resource-juggling that made it necessary in the past, and far more to do with workflow and window management.