To try to answer my own question, I believe the asymptotically decreasing inflation in bitcoins is compensated by its increase in value against traditional inflationary currencies.
For example, on the surface it looks like a bad deal to lend someone bitcoins when almost all bitcoins have been generated. You will most likely receive a very low interest rate. Why wouldn't you just convert to some other currency (say USD), lend money out in that currency, and capture a higher interest rate? The answer is that because since bitcoin inflation will be nonexistent by that time, its exchange value against USD would increase by precisely the amount of US inflation.
For example, on the surface it looks like a bad deal to lend someone bitcoins when almost all bitcoins have been generated. You will most likely receive a very low interest rate. Why wouldn't you just convert to some other currency (say USD), lend money out in that currency, and capture a higher interest rate? The answer is that because since bitcoin inflation will be nonexistent by that time, its exchange value against USD would increase by precisely the amount of US inflation.