FOR CHRIST's SAKE - It's NOT a value judgement and has got nothing to do with being 'blinkered' or 'open-minded'! By standing by accepted definitions of folk song no-one is stopping you from singing anything you like or commenting on the quality of what you or others choose to sing.

Just reflect on the following quote from the great folk song collector, Mike Yates:

"...many people today want a world of certainties, a world where our every thought and desire can be seen in terms of black and white. But, of course, life is not like that, and kicking against this we so often find ourselves suffering from the unsatisfactory nature of things."

This is why you seem to be upset about the fact that, "Almost all people who are currently singing folk songs aren't."
And that last statement may not be completely true - I know plenty of people who choose to sing 'real folk songs'.