Flex -- Label Rotation in ColumnSeries

If you want the label displayed by a ColumnSeries to be rotated, you don't set a "labelRotation" property like you would on an AxisRenderer.  Instead, you set the showLabelVertically property....on the ColumnChart.  I don't know why it's there and not on the series.  It would be nice if I could configure label rotation individually for each series.  More importantly, though, if you use a ColumnSeries, you MUST use a ColumnChart.  (You can add a LineSeries to a ColumnChart, but you cannot add a ColumnSeries to a LineChart.)

In ColumnSeries' updateTransform function, there's this line:

    if(chart  && !(ColumnChart(chart).showLabelVertically))

   
If the chart is anything but a ColumnChart, you would get an exception because the cast would be invalid.
   
The series is merely asking the chart for the value of that showLabelVertically property, so again, why not have it on the series?