Most hardrives live in servers, as part of storage volumes where IO can be optimised well beyond the capability of a single disk.
For the boot disk on my workstation I am absolutely using an SSD, but for the hundreds of terabytes of largely static data that I need to keep archived? Spinning disks all the way. Not only to SSDs need to match on price, but they also have a long way to come in terms of longevity.
When will it be commercially available though? Supposedly Seagate has had 30TB drives out for the better part of a year, but I can't find anything larger than 24TB actually available for purchase.