Metro rakes typically operate at 60-70kmph MPS. At those speeds, the streamlining of the front nose doesn't really matter. At those speeds, the gap between coaches and the empty space below the coaches are the main factors that impact the aerodynamics of the train. The streamlining on the Metro trains is partly for cosmetic reasons and partly to remove some complications while passing through tunnels.
Streamlining becomes important beyond 80kmph or so (Depends on the type of coaches being hauled) and becomes important only at higher speeds. For the WAP-5 , this streamlining should do the job for its operating speed.