Why don't Slideshows Auto-rotate?

In the new Sites theme, homepage slideshows (also known as carousels) no longer automatically advance through a loop. 

Why? The downside can be summarized in three main areas: 

1. Auto rotating slideshows are generally less (or even not at all) accessible. 

From WebAIM expert, Jared Smith, “For auto-playing carousels, having content automatically disappear can cause loss of focus for screen reader and keyboard users that are reading or have keyboard focus on that content when it animates away. This can force the user back to the top of the page. There also is no easy way to semantically or programmatically associate the controls for a carousel—often just numbers or dots—with the carousel content. This is especially difficult for users that cannot see the interface. The cognitive load and distraction caused by carousels can be especially difficult for some users with cognitive and learning disabilities. If, after all this, you decide to implement a carousel, we recommend not having it automatically advance."

2. Auto rotating slideshows are not optimized for mobile use. 

From Nielsen Norman Group: "Do not auto-forward on mobile devices, because: (1) it slows down the page, and (2) because pages are short, users often scroll quickly, so by the time the carousel changes, the user is likely looking below the fold and won’t see the change anyway.” Further, "Users are more likely to ignore an animated item that looks like an ad (if they are not in a shopping mindset). Our eyetracking research reveals that animated ads get looked at 27% of the time."

3. Users prefer to be in control. 

From Jon MacDonald "When a user visits a website, they want to feel like they are in control of the browsing experience. A carousel, with its images rotating every five seconds, makes users feel like they’re no longer in control. Products and deals are automatically sliding past, and if a user happens to be interested in one of them, they have to act fast before the offer disappears. This perceived loss of control can be particularly frustrating for those who have difficulty with motor skills.

It is probable that in a future release of Sites, slideshows will be omitted entirely, in favor of other content types. 

Why? They're not good at getting your point across.

The most pivotal piece research around carousels or sliders came from Nielsen Norman Group and began the revolution of moving away from slideshows.  

A direct review of the issues at hand comes from this Jon MacDonald article that considers the effectiveness of using a slideshow/carousel. 

“… Research by Notre Dame showed that a staggeringly low 1% of site visitors click on non-rotating image carousels (carousels that don’t change automatically). Additionally, 84% of those clicks are on the first slide, meaning all the remaining slides combined receive a paltry 16% of the clicks. 

The numbers aren’t much better for “fancy” carousels that rotate on their own. Auto-rotating carousels receive a bit more attention, but again, the first slide dominates, receiving 40% of all clicks. The second and third positions receive 18% and 11% fewer clicks. “

A few other links for consideration: