I look at IE like the old clunker car that you're constantly having to fix. Some people enjoy a challenge like that, but almost everyone hates having their car strand them on some highway, and not everyone enjoys the near constant work it requires just to keep the thing running.

So continuing with the analogy, Firefox would be like a low maintainance car. You just have to do the regular sorts of things, like check the fluids and put gas in it. You don't need to be constantly running to the car parts store getting some part or another just to keep it running (e.g installing some anti-spyware program). You can spend more time driving and doing other things.