What I'm considering is it's usability as a currency. Obviously if you're making a large transaction, you want to wait a significant amount of time/confirmations. However, if, say, you want to go buy coffee with bitcoins and your local coffee shop, if I were the merchant I would need to wait at least till that transaction had been included in a block. Since the amount used will be pretty small, (like 1-5$) numerous confirmations would generally not be necessary. But if the blocks are at times 40+ minutes apart, who's going to wait that long just to get their coffee? Not me!