I agree. Harman makes some fine drivers that perform well for their price-point, but they do not spend much on trying to make them pretty. I think this is a mistake, because "pride of ownership" is important and "looking the part" definitely assists in sales!
You can't really tell it, but in the photo of the Studio 5 series - the 590 where the grill is removed, has a snap in plastic insert to replace the bottom horn surface made up by the grill.
But the good news is that while, for most speakers, the grill screws up the FR, that happens primarily at the upper frequencies. In the case of these speakers there is never grill over the tweeter, so these are better suited for using the grills!
I'm still trying to figure out how much I like the look! However, someone here made the astute observation that they reminded him of a muscle car from the '80s, and that perspective makes them work pretty well, especially in the larger size!