The argument I like to make regarding the 'inherent value' of Fiat is that you can use it to pay your taxes.
And if Bitcoin and Dollars were completely the same in every single other way, except that the IRS let you pay your taxes in BitDollars (or whatever), then that would be the one that had more 'inherent' value - to me, at least.
I guess the interesting thing starts when the IRS lets you pay your taxes in bitcoins....