Thanks to @nickofthyme's work on the new bubble series, we can now ask the question of whether Lens should support Bubble charts as a separate chart type. For example, we can compare the bubble chart in Lens against the combined Line series + Bubbles in Visualize

In Lens:

In Visualize:

An important part of Visualize is the "size ratio" parameter:

Without considering the timing, the main open questions are:

• Should Lens require bubble charts to be combined with another chart type?
• Should Lens support bubble charts without a bubble size parameter?