Agreed. I have several aluminum enclosed drives with and without fans. They both get hot as the aluminum is designed as a heat sink. In particular, note the bottom of the G-Raid Mini has a rippled metal piece. It butts up against the drive and the ripples triple the surface area, allowing it to conduct the heat away from the drive and dissipate it quickly.
That said, particularly on warm days or when I am at home with all my drives, my router, my computer, my thunderbolt display is all putting off heat, I have a fan to help keep things even cooler. This helps because sometimes when it gets really hot, the drive or computer will spin down a little. It performs slower, but prevents overheating. The fan prevents that from needing to happen. The convection of the air on the aluminum dissipates the heat very quickly.