Never a truer word, Mark. It's not just the uncharted rivers these days, either. There are bits of the local club water on the Welland and Nene near me that never see an angler.
Why? Because you have to walk a mile to get to them. This summer I've waded through knee-high meadow to get to the banks of cracking bits of the Welland, and it's obvious the banks have not been trodden all season. As you say, just because they haven't been fished doesn't mean they hold all the specimen fish; expectations should be the same as you'd have on any other bit of the river.
But the joy of fishing completely alone and ambushing fish that clearly haven't seen a hook is supreme.
The real dream (and plenty achieve it) is happening upon some really great fishing; you can have it all to yourself for as long as you want.
Great article. I really hope it gets some of our more sedentary members off their arses and down the river/canal/lake bank.