This is real life verses ideology and it does show one of the problems with bitcoin.

Its not bitcoin, but the attitude of early adopters, which is very similar to some inventors, where they are holding out for a future that never happens, and kills the moment where they could make a difference.

Money is not for saving, its for spending. Having a store of potential spending is not going to help anyone.  However, that isn't a Keynesian idea, its basic economics. What Keynesians do is borrow other people's money to spend, and when they run out of that, then the trouble really starts!

However, saving isn't a bad idea, the problem is actually the same problem that Krugman missed which is that its not the bitcoins which are good for saving, its their relationship with fiat that makes them valuable.

The only element of the original Krugman quote that seriously needs looking at again is the idea of lending not being possible, and with this I think he is wrong.  Mostly because he is not thinking outside the box.  You can lend bitcoins at a very low level of interest, but only if you don't want to work with a different currency as well. 

Borrow 1 BTC, and pay back 1.1BTC can work over any time.

Ironically, while a large number of bitcoiners are ranting for the end of fiat, without the exchange rate, bitcoin would be more useful. 

How we solve that problem is beyond me at this time on a Saturday!