Respectfully, that criticism applies to carrier pigeons too, which is why we don't use carrier pigeons or email for online transactions; we use payment processors that clear transactions in low single digit seconds.
The same criticism applies to cheques as well as COD, but I don't see anyone saying they don't serve a purpose.
Assuming BTC becomes a generic unit of exchange, the currency promises to save me around $50 to $100 per international money wire and cut the time it takes to transfer funds down to a few minutes. I've had zero failures using the system to date (max transfer time of 20 min), and would need to see a 10% failure rate before it stopped making sense. And that's without even calculating the costs of relying on monopolistic intermediaries like banks for currency exchange.
There are a lot of businesses that have to deal with outlandishly high rates charged by companies that process credit card payments for non-US companies. I'd find it far more convenient to send a bitcoin payment to a supplier in China than have to go to the bank and handle the conversion that way and would also love it if I could exchange BTC for HKD or CLP the next time I'm travelling in Hong Kong or Latin America.