The reason to spend money on gear you don't already have is to do something your current gear gets in the way of you doing.

For me, that was a major reason to go to FF on digital (none of the current APC cameras had the ability to capture scene dynamic range that I wanted and I was tired of exposure stacking).

Lusting after a new piece of gear is not unusual in the photography field - to the point that it's got an acronym: GAS ('gear acquisition syndrome').

I’m adding a couple of images. First one would have been possible with one of my APS-C camera bodies, but I would have had to hand-stack exposures (water ripples). The second one just not possible without a tracker.