What is important is NOT deflation vs inflation, but to keep that value _stable_. USD inflates at a rate of 3% year over year, so we can compare investment vehicles against the rate of inflation and see whether or not they are good deals.
But since BTC is extremely volatile, its impossible to use it as a unit of value. Until it settles down and becomes predictable, it will become impossible to form a "BTC Economy".
As is, though, I think it's already more stable than local currencies for some parts of the world (though perhaps still not more so than the dollar).
"Owning" BTCs is not about churning profits eventually, its 100% about speculating about its future value. Building BTC Mining equipment is where the real "value" of owning BTCs is in, since that puts you in control over a number of BTC transactions.
The BTCs themselves can NOT be compared to stocks. Stocks mean you actually own the company, you eventually partake in that company's profits... and even partake in choosing the board of directors. (who then in turn... choose the CEO).
A BTC on the other hand, is like speculating on Oil, Gold, or Timber. Its a commodity, not a "share".
Ultimately, crypto-coins are a new type of financial instrument that don't fit cleanly into either currency or commodity (given that they're not exchangeable for something tangible). Owning BTC is subjectively stock-like, in the sense that its present value is based primarily on network effects, and its future value is highly uncertain.
What used to be a rounding-error that happened on every BTC transaction is now a $0.10 tax on every BTC transaction. If BTC continues to deflate, the transaction fees on BTC are going to become quite sizable.
The high level idea is to introduce market mechanics to bitcoin fees, with the expectation that competition will drive prices down.