It was a one-off experiment to improve ALCOs in the same style as EMDs. The WDM3D locos used a lot of features from the WDP4 series locos like microprocessor control, electronic fuel injection etc. This loco and some others from GOC/EMD with the slightly pointy shaped front cab, were experiments to emulate the EMD style cab.
Also, having a 'V' shape at the front doesn't really correlate with higher speeds.
Until about 140-160kmph, the shape of the loco doesn't really matter unless it's...
more... a short rake.
The aerodynamic performance of a train depends on 2 things - the shape of the loco and coaches (streamlined front face, how wide and tall the loco and coaches are etc) and the length of the train.
For most Indian trains, the drag due to the length of the train is much higher than the drag due to the shape of the loco. So, streamlining or not streamlining the loco face doesn't really make a big difference for IR's trains.