The thing about bananas is that people will eat them (or at least find a use for them) until they're well-past ripe and verging on brown. But if they're green? They're basically useless, suitable for nothing more than causing constipation. Heck, you wouldn't even use them to make banana bread!
Sometimes, though, you just want to eat the fruit before it's ready but don't have three days to wait until it's that perfect yellow with only a handful of brown freckles.
This is where the microwave trick comes in.