Seriously all they need to do if they want cores to stay is lower the cost to masterwork.
Instead of the extreme progressive tax they should lower it to 1 core per upgrade and the community would be satisfied, given everything else stays the same.
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The whole concept of grinding all season for enough cores to upgrade some of your gear (and likely not fully masterworking much if anything) and then in 3 months you have to repeat the exact same grind again is just not fun.