I'm with you on those other aspects being very important, but I'm not sure they are more important in general. After all, relatively few APIs are truly essentia

I'm with you on those other aspects being very important, but I'm not sure they are more important in general. After all, relatively few APIs are truly essential, offering access to some exclusive facility that users of that API couldn't also find somewhere else and/or implement themselves. For everything else, unless you can hold enough of a potential user's initial interest for them to carry on trying things out, the other stuff doesn't matter.