Useful for heating large pads on SMD devices. Sometimes you need a different size to fit the area you are working on. Heat, solder, remove immediately. Seriously, you need more than what comes in the kit.
I bought this as a possible replacement for the original tip that came with my WLC soldering iron, but it's a little narrower and I found it better. This is official Weller advice, so the quality is to be expected. But it has a flattened tip, which is very convenient for working with DIP pins.