More good questions I see...
That motor a 1977 Long Shaft 150HP Merc. After market Nose Cones fitted to standard "fishing" motors improved speed slightly and improved handling plus they provided for added safety at real high speed. Under APBA rules, Nose Cones were not permitted in most
classes of outboard power boat racing in that era. Know one would ever dream of racing a Long Shaft motor unless it was powering an offshore racing hull, again the rules would have still prevented any Nose Cone being fitted to a standard motor.
These days, both after market and factory fitted Nose Cones can have low water pick ups, which on some boats and applications can be advantageous.
These days, Merc sells a range of optional standard looking gear cases with Nose Cones for their V6 range of motors. These gear cases are designed to go under their high horsepower outboards which are capable of pushing high performance hulls well over 180kph.
These days you can even buy very good after market Nose Cones which are relatively easy to fit. http://www.bobsmachine.com/Nose-cones-low-water-pickups-Kits-and-accessories_c21.htm
If you are dawdling along at speeds of 110km or less, it's hardly worth thinking about or bothering with a Nose Cone. You wouldn't notice the difference.