How Important is Experience, really? (Reprint from BRPCentral Blog)

Experience is pretty essential for life, right? We experience things and (hopefully) learn from our triumphs and mistakes. It works the same way in role playing games because you are a person (or robot) and people (and robots) grow through learning. Even if that learning takes place at the business end of a blaster. I mean, who doesn't watch Solo and Greedo and think "Yep, I am gonna shoot foist EVERY TIME!".  I suspect that comes out of he grading system found in many war games. (Again, don't know that for sure.)
I liked the experience system in d100 games, starting with Runequest when I played that. At the time I was playing though, experience was a big deal. As gaming has progressed, experience seems to be less and less relevant as campaigns become shorter and shorter or gaming becomes a series of one shots. This is not a bad thing, but can call into question time spent on designing the experience system of a game (or blogging about it... maybe).
I still think an easy to follow but meaningful experience system is important, as is a system that allows for the creation of characters at a certain power level. So in essence you need 3 experience systems.

1. Traditional medium to long term experience system that helps characters develop over time.
2. A faster system that gives the feeling of change over a short number (2-4) of sessions
3. A Jump Start system tied to character generation that lets you create an experienced character of a certain power level. 

Keeping number three in mind I am considering using a Life Path style character generation and having extended life events for higher power levels. Unlike a class based system you just can't pick a level and go.