This is because you have comfort mode active: It's there to keep you from getting motion sick and barfing!
You can turn it off but........ Hope you have a strong stomach.
After a Year of Flying games Space fighter games, DOOM 3 VR the only thing stat still gets me a bit queazy in VR is when i scale myself up or down in google earth.. Going from person sized to 10,000 feet tall is gut wrenching