It's kind of similar to audio vs video. Although audio requires less data and processing than video, it's much more difficult to get the audio good than the video and if the audio is bad or even missing for some time, it's useless, while if the video is bad, stuck or missing, it's not that big of a deal most of the time.

This is particularly true in a video conferencing situation. If the audio is bad, you miss out a lot. If the video is bad, it's not a big deal.