Yes, when case designers and all those molding engineers install drive bays, they truly DO imagine people using them. A lot or all of them. If anyone's noticed, file-sizes HAVE increased, ergo file-storage needs an increase, and storage devices therefore have increased.
And as DRM and subscriber services strangle more consumers, some folks say, "No thanks, I own a copy myself and I'll watch it/use it on my schedule on my equipment."