Measuring the Cost of Ownership isn’t your primary focus when you want to find out why you don’t have as many developers using your library as you would like. It might be reasonable to analyze the cost of ownership, if you used to have developers and are now losing them. However, if you’re just starting and you need to attract new ones, the cost of ownership is probably not the most important criterion to use. People may trust your library more if you have a good reputation with respect to BackwardCompatibility (which reduces the cost of ownership). However optimizing the Cost of Ownership may not be your primary concern when you need to optimize for Time To Market.