Well, like everything in photography, there are tradeoffs. Shooting with a small "f" number, i.e. a wider aperture, it is easier to stop action or work in lower light since you are taking in so much light but depth of field diminishes so focusing becomes more critical. That's not all bad, though, since having everything other than the subject slightly out of focus is a nice effect.
But, hey, just because shooting "wide open" maximizes light, it doesn't mean you have to do so if you have plenty of light at other, smaller apertures. Stopping down to f4 or 5.6 gives you greater depth of field. But having the ability to open up past the limits of many moderately priced zooms can be a life saver in lower light situations.