I recently assisted an NGO, Selamta Family Project, with refreshing their website. As part of the process, I worked with the client in selecting a new WordPress theme for the site. What was interesting about this is that we started out with one purchased theme, but ended up switching to another. The first theme we selected was specifically tailored to non-profits and had many previous sales on ThemeForest. It did a particularly good job integrating calendar events with WordPress.
In my view, the animation effects commonly found in newer website themes reflect an increasing emphasis on capturing the viewer’s attention and keeping their interest once they land upon the home page. Visitors to a website are unlikely to delve in and click through various links in a navigation menu, so the newer themes include many techniques to help impart information in an interesting and entertaining way on the landing page itself, in hopes that the viewer will stay long enough to become interested in contributing to a charity or making a purchase on a commercial site.