Perhaps EK figured that the redemption value to amount being spent was too high and so decided to rectify it. By making the lower fares earn at a lower rate hardly seems insane. Istr lots of issues raised about the number of gold members and it sounds like the enhancements may well have raised the bar for some

Is it reasonable to change the scheme, well yes, they own the scheme. Those who choose to be members have to decide whether they want to accept the changes and continue participating or to collect miles to another scheme or change carriers

If EK lost too many passengers to other carriers I am sure that they would reconsider whether they want to keep the changes

Just complaining how it is unfair or unreasonable is and how it shoudl be changed, to me, on par with hens in a henhouse declaring that foxes need to become vegetarians