Actually, this problem seems to be limited to devices with Play Store available, so Nexus 5X and Nexus 5 images will be forced to use Automatic Graphics, but all other devices allow you to choose either Automatic, Hardware or Software graphics.
edit: I’ve just tested this today and it seems to no longer be the case. At least on MacOS with Android Studio 3.3.2, I can now make a Nexus 5X image with Play Store and Hardware Graphics. I’ll do more testing at home later, on Windows and Linux to see if it’s related to OS or graphics drivers.
