It fills the niche of "pointing device that uses a constant amount of deskspace" in the same way that a trackball does, but differently. Different strokes, different folks.

NGL I was always a fan of TrackPoints for how compact the pointing device was. Also liked the Logitech Trackman Marble for similar reasons. It's kind of cool, though unnecessary, to have a way to get a TrackPoint on a desktop now without being locked to one discontinued Lenovo keyboard.

I'm typing this on a Thinkpad Trackpoint II keyboard and have no idea why I'd want an off keyboard pointing stick. If you want to use a pointing stick why not have it right next to your index finger while you're on the home row? If you want your mouse cursor control to be off of the keyboard, why not use a regular mouse?