The announced tax percentages are in line with the South Korean tax code for all corporations that make a yearly income of over 20 bln won ($18.7 mln).
It's in line with the country's current tax code, so there is no anti-cryptocurrency campaign going on. If the exchanges are operating in South Korea, then they have to follow South Korea's tax laws. Every other company does.
The 24.2 percent tax is taken from the exchanges' profits, not the trader (unless he makes obscene amounts of money to end up in that tax bracket). Part of this is inevitably going to be shouldered by their customers though, so that kind of sucks, but it's also fair. What would be unfair is if they charged higher taxes for crypto-based earnings, and they're not doing that.