It seems to me that IS are picking a fight to try and get 'crusader' forces on the ground in order to take more life and also try to create a jihad against the Great Satan (other terms are available).
Jordan called 'bull****' on them by demanding a proof that Lt al-Kasabeh was still alive.
The $200M demand for the Japanese hostages was also so large that it was clearly just a 'come on'.
They are not warriors.
Just depraved, criminal thugs - seeking to cause mayhem and make themselves legends in their own warped minds.
As they are being beaten on the battlefield, they need to try and gain some 'kudos' from another 'spectacular'.
There is no way that on their day of judgement that their Maker will ever determine that they have been righteous.
Time to send them the love - thermobarically speaking.