When you want to have a look at a longer timespan with lots of data, it might get difficult to visualize the detail of the values of each individual point since the lines that connect each point are hirering the individual points.
By using small points (size could be configurable) you can see the cloud of points and therefore visualy understand where the values are positioned on your trend.
Thickness of the line between points, when used, could also be configurable.
See an example:
Thanks in advance for supporting our idea.