You have to break them down into 3 groups or more.
The knowledged, the ignorant, and the insane.
For the ignorant members perhaps they think its to get current PS4 owners to upgrade so Sony can make TONS and TONS of money selling these new systems.
The only problem with that idea is that Sony/MS business model is to sell the consoles near manufacturing cost, and make little profit off of it, instead making profit off of PSN subscriptions, accessory markup, 3rd party royalties, 1st party games, and now digital distribution via the Playstation Store. Infact Sony is potentially negatively impacting profits in the short term on adopters who would either would have had lots more money to spend on games (current PS4 owners switching to PS4K), or those without a PS4 at least $100 more on games, had they gone with the regular PS4 rather than the more expensive PS4K.
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For the more knowledged members, perhaps they think its multipronged and yes for VR but also to get gamers to stay with PS4 rather than migrate to PC as superior to PS4 components become cheaper and cheaper. Perhaps also its to entice future gamers who are on the fence about buying a decent gaming PC or PS4 or $100 cheaper Xbox Ono.
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For the insane members
Its to counter the upcoming DX12.1 (or possibly 12.2) release on Xbox One that will unlock the dark Silicon hidden ALU layer 2.6TF DP (5.2TF single precision), 10TB/s internal Esram bandwidth, that has Sony execs crying themselves to sleep every night.