This is the recorded talk I did with Game Economist Ramin Shokrizade about trying to make ethical F2P Design. For more from Ramin, here are a number of his articles on the topic:
http://www.gamasutra.com/blogs/RaminShokrizade/20171207/311179/Consumer_Friendly_F2P.php
http://www.gamasutra.com/blogs/RaminShokrizade/20171031/308600/How_the_ESRB_is_Promoting_Childrens_Gambling.php
http://www.gamasutra.com/blogs/RaminShokrizade/20151005/255285/Secrets_of_F2P_Threat_Generation.php
http://www.gamasutra.com/blogs/RaminShokrizade/20131022/202782/Compassion_in_F2P.php