Isn't bitcoin being deflationary one of it's highlights and selling points?
If it wants to be a 'real' or useful currency, being deflationary isn't such a good thing to be. The points mentioned in the initial post describe the disadvantages of deflationary currencies. It's great for people who want to see their investment appreciate in value, but not for people who want to use it in order to buy stuff!
If an economy is based on a deflationary currency then it would be a bad thing as people would have an incentive to not spend money when they need to buy something. This creates a situation when there is negative economic growth. If an economy has a secondary currency that is deflationary then this would not be an issue.
Control question: Why would anybody offer to sell anything at all in the current inflationary environment, when they can get more by holding the things and selling them next year?
Because most people don't live off bitcoins mined/bought at 1 dollar ? The farmer can't hold his tomatoes or peaches, either he sells them or they're worth nothing. He can hold grain though, and this has caused famines.
What is needed is neither inflation or deflation, both are bad. But the main problem isn't even there, it's in things like development, growth, way of life, etc. What do we want to achieve, what can the environment sustain, what will happen when all the Asians and Africans will be able to buy a car and an iPhone, etc.
I don't think Bitcoin is much help in this matter.
Most of you seem to be hailing from the US, so I will describe what's happening here in the Eurozone where deflation is upon us, thanks in part to a strong Euro : no economic growth and high unemployment. Good or bad, you decide, but it is what it is.