It's all cosmetics, the drives are still sealed (with the exception of a filtered ventilation port) regardless of how they look. Filtered ventilation ports are designed to allow drives to breath. This allows the drive to operate at different altitudes without creating a vacuum or pressure point, that could warp the drives housing. If you start placing tape on the drive, you could risk blocking the ventilation port. There is also the risk of creating an insulated heat barrier with tape, which could cause the drive to get even hotter than normal when heat dissipation is reduced. Though simply covering a small hole would likely not effect heat dissipation at all.