The problem with fixed bitcoins (and while I like btc, I think it is a real problem) is that when you eventually hit 21 million BTC, you only lose bitcoins from lost wallets from that point forward, so the money supply shrinks over time and the currency deflates with no way to get back lost coins.
Deflation is bad because then you can sit on btc (like people are now) and the exchange rate goes up because they gain in scarcity. They aren't really useful as a unit of exchange then, there was a story a day or two ago about how btc (while improving) still has 1/3 the turnover rate of fiat market currencies because most people are holding them as an investment.
A part of that is that btc isn't widely circulated for exchange yet, and sitting on it instead of a savings account makes sense when the speculative market is going through the roof. So even if you wanted to spend it, you still have to translate it back into fiat currencies and use those right now.
Deflation is bad because then you can sit on btc (like people are now) and the exchange rate goes up because they gain in scarcity. They aren't really useful as a unit of exchange then, there was a story a day or two ago about how btc (while improving) still has 1/3 the turnover rate of fiat market currencies because most people are holding them as an investment.
A part of that is that btc isn't widely circulated for exchange yet, and sitting on it instead of a savings account makes sense when the speculative market is going through the roof. So even if you wanted to spend it, you still have to translate it back into fiat currencies and use those right now.