While I feel for Foo Fighters fans (some work colleagues and James' girlfriend Tara among them), I don't see the issue for the Glastonbury audience.
In my eyes, Glastonbury ticket holders aren't really being short-changed and in any case a single act should not the main reason to go to a festival any way.
It is short-notice to withdraw, and gives the organisors a bit of a headache but I can't see that there is any need for the amount of bleating that is doing the rounds from music fans.
If you like a group and they cancel, it is a shame - but this is not the first time (in recent times U2, Neil Young and Kylie Minogue have all cancelled for various reasons) this has happened and won't be the last.
If you have booked tickets for the World Tour, I am sorry for the news and wish Dave Grohl a fast recovery but otherwise can I suggest that you get on with life and look forward to a great Glastonbury Festival in just one week's time.
Aye, Thang Yoo.
<More Glastonbury 2015 Thoughts Here>