Taking the example of the keyboard:
There is no doubt that using a conventional mechanical keyboard in VR will ultimately be great for those who want to type fast/best. But the correct path to it will be… first just a clumsy keyboard that HMD users have to peck at with hand controllers (like we have now with the steam keyboard). This will make traditional keyboard users unhappy! In a couple years, as the lighthouse and tracking marker technology and pass-through cameras become better, it will be possible to equip a traditional mechanical with trackers so that you can see it when you get close to it, and see your hands above it with the pass-through camera. So… once VR reaches maturity, there will be a number of great options allowing full speed keyboarding. But the immersive world must come first, which will break certain things for a while (no mouse no keyboard).
Doing in the other way is what would be wrong: Assume that everyone using VR must have a mechanical keyboard with arms reach, and further assume that many are also touch typers (meaning you can use it blind with the HMD). Critical commands need to be entered on the keyboard or using the mouse, so that means seated experiences initially because if you stand you can’t carry your keyboard. So the richness of the new immersive experience suffers to allow the keyboarding experience to be first class. This approach will fail.
I guess the summary is this - we should let lots of things be bolted on, like the keyboard or mouse. But we must be very careful not to do that in a way that takes away from enabling the disruptive new experience of being able to do everything with the HMD and hand controllers.