Each laptop needs at least 256G, I would prefer 512G - as that would allow the comfortable use of HyperV setups within the laptop (it would be easier to separate a business environment from that of a personal one within the hyper V, and it would make migrating between laptops easier. I would also like 16G of RAM - but usually only 8G is available in most ultrabooks currently.
Workstations need at least 800G of SSD for speed - not only boot, but any local operations as well (CAD, Visual studio - they all work better with faster local storage).
10GBase-T networks are much more affordable, and are standard on many server motherboards - these need SSDs to keep them fed at max data rates.
The servers definitely need SSDs, and lots of them. They are used for the boot drives, the hyper V drives, they are all redundant, and the servers have redundancy as well.
The only thing I see use for magnetic HD for is longer term backup storage (or near term as well - for pricing reasons currently), video storage, as well as security footage. the rest is SSD.
Any large server environment, doing a lot of DB work, or multiple virtual servers etc would not be able to do this without SSDs.
The next level will be NVMe drives. I have used one in a workstation, but have not migrated any servers to them, as I prefer to have hardware RAID, and none exists for them yet. I think the Intel news will allow more affordable 4-8TB NVMe drives - a bank of those in a server would provide incredible performance.
I would agree, if your maximum use of a computer is web browsing, and the occasional word processing, not much performance nor much storage is required. For anything more intensive than that, having more power does provide benefits.
