Grant doesn't think you need them:

"Racing shoes are rigid, slippery plastic. Riders shopping for them pick them up and test their stiffness (as though it matters) by trying to bend them with their hands. If the shoe is rigid and unyielding, they heave out an "ahhh..." and consider it worthy.
It's a bunch of hooey, though. Your foot doesn't bend when you pedal a bike. It tenses and pretty much stays straight, just as it does when you walk up stairs.
You want TWO things from a shoe:
protection from the pedal. You don't want to jam the pedal into your foot.
gription. You don't want to slide around on the pedal.
That is all."