Giving money on charity websites is 7% more difficult than spending money on ecommerce sites. Donating physical items is even harder. For non-profit websites, social media is secondary; the top priority is to write clearer content.
Although the gains don't fall into traditional profit columns, there are clear arguments for improving usability of non-commercial websites and intranets. In one example, a state agency could get an ROI of 22,000% by fixing a basic usability problem.