Legends and tooltips are a requirement for replacing pie and donut charts in Kibana. The main reason is that when rendered in a dashboard, it's not obvious what the visualization shows without the tooltip to indicate the source of the data.

The legend and coloring implementation that exists in Kibana combines all values into a flat legend, regardless of the layer it's displayed on. That behavior might not be needed if we can come up with a better way of displaying legends.

While there are customization options in the current implementation, they are pretty minimal. For example, the legend can't be hidden.