It IS relevant when you have only 2 blocks created in 40 minutes (like right now) and a merchant that requires at least 3 or 4 confirmations.
The Bitcoin confirmation time is about protecting from double spends. So 1 confirmation means it's unlikely the transaction could be reversed as in you would need a hell of a lot of mining power. 6 confirmations and you're transaction is pretty solid.
So a merchant would generally only wait for confirmations for large transactions. For small transactions it is enough to detect the transaction is in the network, i.e. more or less instant.