A bit worrying, assuming something should not, rather not, bad taste etc. Beauty is in the eye of the beholder. Bad enough the BBC saying what comics can say and can't.
The original song has all the pathos, respect, lessons from history and everything else you may care to mention. However, it was, a few years ago, played by all and at regular intervals.
Methinks the status of the song as one that gets sung all the time does lend itself to parody, albeit for the oversinging rather than the subject matter.
Two things there;
1. I used to sing a parody of another song that was overplayed in folk clubs, Thompson's Bright Lights.
"Meet me at the folk club, don't be late
I need to sing some Richard and it just won't wait.
Blow out the candles and turn on the lights,
I don't want to hear "The Bright Lights" tonight."
2. It is suggested above that WW1 parody is not acceptable. There are those out there who feel Bob Dylan songs have some hallowed status too. Yet Eric Bogle wrote a wonderful song parodying the fact that wherever he went, people expected him to sing Dylan songs. So I doubt he for one would complain about the same done to his more serious songs?
That said, the example in this thread isn't one I would personally want to expand on.....