A big part of the complexity is inherent to dual-boot. Dual-booting Macs is a touch more complex than the usual because the firmware is "Apple EFI" not UEFI and not legacy BIOS, and no firmware setup. Next Arch has only recently developed a GUI installer. Several distros have mature GUI installers. So the trouble is partly about the choices made. Even OS X + Windows dual boot quickly gets really complicated if you want to do anything that Apple doesn't directly support in Boot Camp Assistant.