XAML Team recently reviewed this request and decided not to address it in the future since the Smart Labels functionality was introduced in Q1 2014.
I believe I am the original requester for this feature, and Shinand is correct; this is about axis labels overlapping into a mess, not smart labels.
Hi Telerik team, I believe the requested feature is about labels on the main axis, not data labels on the chart like Smart Labels. Right now we currently have to write a bunch of code to skip some axis labels as the chart is resized.
Please let me know when this feature is available thanks :)