It's the best part of the pen! So a few things on this style of pen:

The click-pen makes everyday use very viable because there's no uncapping time. Just click and go. Plus it's fun!

These pens come with refillable cartridges with little rubber stoppers that not only expand the ink capacity to the maximum, but show allow you to pre-fill them so you can spend less time messing around when changing cartridges.

The cheaper price tag allows you to pick up a few for the same cost as a more expensive pen, adding to the "everyday carry" value as you can lose/damage one without a massive loss. Obviously one wants to be careful with their things but on the off-chance your pen goes missing, you can replace it very easily!

I realizenow that I should shoot a video on this particular topic. Bahahaha