I agree with you to a great extent, a currency must have some sort of stability for it to be truly valued. I honestly hope that bitcoins settle at a price in the near future my heart can't handle this much excitement every day.
If I was a some sort of vendor I wouldn't accept bitcoin at the moment unless they were immediately cashed simply because I'd fear selling a computer for $1500 worth of bitcoins then watch that fall potentially the next day.
When bitcoin stabilizes, the marketplace will be more and more willing to accept them as a payment option.
To be clear, I didn't write the article, I merely posted it here for discussion...
However I am able to partially validate the author's point in that I too act as if Bitcoin is an investment. In fact, I now regret using it as currency when I traded almost 100 for an Amazon gift code last year.