To begin with, its compulsive well-meaning earnestness, with unmeaningful and inappropriate metaphors. And then the tune is highly uninspiring.

The tune, too, in my opinion leaves much to be desired. A vast ho-hum

And as to why a number of people have sung it? Three reasons come immediately to mind:
1. The attraction of a song with the name Pete Seeger on it.
2. The desire to be seen as earnest and well-meaning.
3. No taste.

Dave Oesterreich