I think your both missing the point. People say the issue with Bitcoin is they don't have much use for it other then speculating on the future price. That issue is being addressed when they have the option to use Bitcoin for their everyday purchases. Now if someone needs something and can use a Bitcoin that is one less reason to deny Bitcoin's value. ...
Yes, it does give Bitcoin more purpose and credibility, its one less reason to deny Bitcoin's use. Not necessarily its value. Here's the deeper economic point: its depleting its value, as you valued the purchased item more than you did the Bitcoin. With normal currency this isn't an issue as the vendor values the currency. However here they don't, and promptly offload immediately. This is not a good thing long term, its a constant selling pressure on the currency.
I find this notion that people are aquiring Bitcoins in the market to then spend at a normal retail establishment to be quite odd. Its daft to purchase something only to use it to purchase something else, where that interim step is unnecessary. I'm sure there some cases, some for the novelty or to see how it works, or edge case financial situations. But it doesn't make much sense to risk the loses in exchange or the transaction costs to do so regularly. I expect the vast majority of Bitcoin sales through regular retailers are from self-mined stockpiles.
What I think will become more common in the future, is the fact that people will buy bitcoin and spend it in order to take advantage of discounts for paying in bitcoin as merchants will have much lower costs with accepting bitcon payments verses accepting a credit card payment.