I think when The Weather Channel TWCC bought Wunderground these changes started to happen.
The old Interactive Wundermap worked well to watch an approaching storm. It was responsive and a joy to use. The New Improved version is not intuitive and a pain to use. The playback head ( the little arrow ) moves across the entire width of the screen above the entire time line yet the time playing is not the entire time line. It is no longer possible ( or I have not figured out how ) to watch the last 30 minutes to judge when the storm will pass overhead. I see no way to control the interval between individual frames. At least when introducing the new improved version with lots of neat new data Wunderground/TWCC could leave a link to the old tried and true version available. I am seriously considering delivering my weather data elsewhere.