Time commitment 

I think the reason why photographs remain popular even though video conveys more information is that the time commitment associated with video is much larger than that of photography. This applies to all aspects, starting from production, where editing takes an enormous amount of time from a photographer’s perspective (in my experience, and I have heard others confirm it, the rule of thumb is one hour of editing for every minute of video for short clips.) The content consumption stage, i.e. watching a video, also requires more time that watching a photo. A photo can be hung on a wall and enjoyed every time our eye falls upon it, while a piece of video mush be viewed in its entirety to be appreciated.

Also, paradoxically, a good photo can potentially engage the viewer more than a video would precisely because a photo contains less information (there is no sound, no physical movement, etc.) Therefore, the viewer has to rely on his/her own experience and imagination to fill in what is missing in a photo: e. g. how fast is the sprinter running? How strong is the wind? How hot is the weather? Perhaps, a good photo is a kind of collaboration between the photographer and the audience, and that is why it can be both produced and enjoyed with a limited time commitment from either side.