At the moment, a huge part (nearly all) of the bitcoin economy is made of exchange with other currencies, mainly USD. Just see how everyone's so worried about the future of bitcoin (sic) because the main exchange place was compromised. That tells a lot about what bitcoin means for everyone.
Totally agreeing with that. Most people see BTC simply as a proxy.
As you say, the only way to get an independent notion of bitcoin's worth is by thinking about what you can buy with those coins you just received as a payment. This means we need to stop focusing on the exchange to get coins, and set up more goods and services, so that bitcoins can exist within their own ecosystem. I need coins? OK, I'll sell some goods or provide some service. Exchanging should only be a side solution if we want a sane currency.
This is exactly why our primary goal (besides increasing the client security for vanillas) should be convincing more shops or other business-people to accept Bitcoins.
As you said, BTC will only get strong if we manage to create an own ecosystem for it.
But for BTC it's going to be substantially harder to establish than for other currencies since the use of BTC isn't forced onto people.
BTC simply needs more trust and that can only be achieved by increased security and more services that you can buy with BTC.
Let us say, for instance, that I have a bunch if Bitcoins and I sell some of them to purchase raw materials for something I am going to manufacture and then sell for Bitcoins. Those materials cost me 1000 BTC on May 22, 2011, my total cost for manufacuring, marketing, etc, is another 1000 BTC, paid on June 5, 2011, and I sell my product for 2200 BTC on June 12, 2011. I have made 200 BTC. "That's only a lousy 10% net you say."
While you are bringing 100% valid points and I agree, the whole "thinking in bitcoins" still has some flaws:
First is, that at the moment it is not possible to buy materials in BTC (and then convert it into products which are being sold for BTC).
You can, of course, buy materials for USD/EUR/GBP and then calculate their costs into BTC, but since it is not possible (YET) to buy food or clothing or to pay your rent, electricity bill or fuel with BTC, you cannot solely rely on BTC for your living.
As long as we don't have enough shops, no own ecosystem for BTC, it will simply stay the proxy for other currencies that it is right now.
Second, albeit you of course cannot simply look at BTC with a constant exchange rate for USD or other currencies, one thing remains pretty constant, and this is workpower.
At the moment I can say that 1 hour of my work is netting me 14 Euros. Even with inflation counted in, i can still buy bread or milk at a very similar rate than it was the case 2 or 3 years ago.
Now we have seen crazy price-jumps of the BTC conversion rate from 1$ to 30$ within not even 2 months and even if you are strictly consistent with "thinking in Bitcoins", you surely wouldn't get the same amount of goods for the workpower you provided during these fluctuations.
And there's a simple reason why: You don't get paid in Bitcoins!
This is, to be honest, the single most concern I have with the bitcoin-system in general. All other currencies have a country where they are enforced by the governments and where people will always get their wages paid with that currency.
BTC does not (and cannot) have such a thing and this will be a major obstacle to some in the way of establishing BTC as a "real" currency.
I know, however, that BTC is still very young and can perfectly imagine that BTC will have an established own ecosystem somewhere in the future.