sucky currency conversion rates they refuse to update

This goes one way or another, some countries benefit from the unchanging conversions

they take 30% cut

I don't know how expensive it is to run Steam, and they certainly could afford to lower their cut with how much infinite money they have, but with how much Steam offers to developers and the potential cost of bandwidth, it doesn't really seem that bad?

they are banning games on behest of Mastercard and Visa

The alternative is to be cut-off from those payment processors and only take money through some other means