Can't say why this is not available anymore. It would indeed make sense to be able to click on a certain datapoint in the chart and get a details page. You could either create an idea in the forum and/or you could create a support ticket to see if you can get additional information about the reason for dropping this option.
As an alternative you could look into the AnyChart solution. It is not as straight forward as the Charts options (but easy enough to understand), but it will give you an option to use a parameter in the on click microflow.
I have used this myself to display details of the selected object next to the graph