Alright so I'm not sure if this was just changed for CBT 2 since I never used it in the past, but the current set exchange rate of 150-250 NCoin is a terrible idea.
1. I guarantee this will not solve the bot problem at all, the currency exchange will just be turned into a useless system because player gold sellers won't be able to compete with bot rates
2. We all know THERE ARE players in ever game who buy illegal gold, otherwise bots wouldn't exist. We also know that the NCoin seller (or the person who pays real cash) wants the maximum amount of Blade And Soul Gold possible. Currently with a simply google search you can see that in TW the rate is about 1.6 gold per NCoin (1,000 gold for $20 or 1600 NCoin in our case) compare that to our current rate of 1/150th of a gold per NCoin at the best possible rate. Now tell me who you would buy from?
3. In every other game the are almost no restrictions, or their restrictions are based off of the recent average exchange rate among players. And a lot of the times people might want to make a deal with another player and have either a higher or lower rate.
4. I think maybe they did this to appease the F2P audience who is complaing about high costume rates so essentially they can buy a 2000 NCoin costume for just 10 gold, but thats the wrong way to do it. You have to build the system around the ones who are trading the more valuable items (in this case real money) or else they'll just take their business elsewhere (bots).