Longterm Bitcoin has to gather enough fees to survive, without fees no miners.
Or in your business language: We can give away our product for free, said no successful business ever.
edit: the fees will longterm lead 1:1 to Bitcoins security. the higher the gathered fees the higher the security of the network.
Without fees, no miners. So people will pay fees to keep their transactions getting on the blockchain and miners will select transactions which help pay for their business. This isn't rocket science.
The problem comes when someone comes along and interferes in this negotiation between customer and service provider and distorts the value proposition.
More explictly: by Greg's argument, the UN should impose a worldwide production limit of 1 million liters of soft drinks per day. Otherwise, the manufacturers like Coke and Pepsi have to give way their products for free, they would go broke, and there would not be enough soft drinks for everybody.
BITCOIN: The world's future global value transmission system, secured by 1000 PH/s of mining power and by a developer team who would bankrupt a homemade lemonade stand on the first day.
To be fair, in your analogy, Coke/Pepsi are *required* to process (bottle and ship) 1 million liter bottles per day, between them. This number is set in stone -- they can't opt to make more or less.
They are currently paid 25BTC every ten minutes to do so, regardless of what they stick in the liter bottles -- Coke, Pepsi, or piss -- that's up to them.
Arguably, it's in their enlightened self-interest to put Coke/Pepsi in the bottles, because they could sell those. In practice, the extra revenue is negligible, and, at times, putting piss/absolutely nothing in the bottles makes better economic sense.