When we're talking about small files, it's not a huge deal. However, when we get into enterprise-level storage, you damn-well better be unambiguous. For instance, I design security systems for a living. If I have a customer with 100 1080p cameras that wants to retain video for at least a year at standard settings (8 FPS, H.264 encoding, 30% compression) recording 24/7, I would need to give them roughly 1 PB of storage.
1 PB of storage (1,000,000,000,000,000 bytes) is not even REMOTELY close to 1 PiB of storage (1,125,899,906,842,624 bytes). If I tell my supplier to give me a SAN with 1 PB of storage when I REALLY mean 1 PiB of storage, I'm going to be ~126TB short. That's a 5-figure screw-up that's going to come out of my paycheck (well, they'd probably just fire me, but you get the idea).