Air Profit. As pointed out by FreeHills above, you seem outraged at the fact that two pilot groups are being treated differently, but this has been the case within CX for ages now. Did you throw the toys out of the pram when B-scale/C-scale/Cos18 was introduced? Surely those were blatant examples of pilots doing the same job within the same airline, but on vastly different pay packages?
Whenever there is a discussion about how HKPA should be increased, the usual response is "They know what they signed". How is this any different? CX guys knew what they signed when they joined, there was no guaranteed 13th month. KA guys signed their contracts, and then fought for improvements.
I half suspect that the 'injustice' that you feel when looking at what KA get is because for a change you happen to be in the group that is worse off, as opposed to the group of pilots within CX who have always had it better.