Belt drive and gear hub is an awesome combo indeed. I'm spending a stupid amount of money to build a gravel bike with that setup, since it doesn't really exist.
I like a different aesthetic but to each their own. A bike you love is the best investment you can make.
There are some that use Shimano Alfine, like the Priority Apollo and Shand Leveret, and others that use Rohloff like MiTech R-Gravel and Shand Cycles Stooshie Rohloff. They're still much rarer that derailleur bikes, though the latest innovation is using a rear derailleur and a 2 speed gear hub with the Classified Powershift.
I like a different aesthetic but to each their own. A bike you love is the best investment you can make.