Shiny smoothness seems to be de rigueur in the persuit of the fastness.
Someone asked Mike Burrows about laminar flow, and he gave a great explanation, including golf ball dimples, why you can't achieve it on a jumbo jet, but almost can on a (streamlined) bicycle…
Shiny smoothness is good, as long as you can keep the laminar flow attached to the surface for lower skin friction, but keeping it attached is the tricky bit. Whenever the flow breaks away, it becomes turbulent. Fortunately bicycles don't go very fast, compared with jumbo jets, although BM speed bikes are a whole other league from domestic bicyclists. A highly refined body(shell) shape that operates in reasonably well standardised conditions, that is, IHPVA-legal wind velocity and air pressure, on a road surface that is without curves, can be expected to behave more predictably, although the conditions are equally no substitute for a wind tunnel, but on balance there is less need for micro-textured surfaces a la golf balls.
The dimples on a golf ball take laminar flow at the leading portion of the surface (and thus highly turbulent flow downstream, because the rate of change of radius after the leading portion is too great) and pre-turbulate it. This micro-turbulent layer is more stable than the laminar, even though the skin friction is higher, and so the overall drag is reduced. You have dimples all over a golf ball because every point on a ball can be the front or the sides. What is not commonly realised is that the dimples aren't all the same depth: those on the 'equator' are very slightly deeper. Given the correct positioning on the tee, and given the correct amount of backspin, this can net you a couple more seconds of flight time, which is good for an extra 20 to 25 metres on the driving range.
Shark skin, and its arrangement of dermal denticles, is optimised for reducing hydrodynamic drag by applying the same turbulising effect. You find that the crowns of the denticles are smooth and nearly flat on the leading edges, like on the snout or the fins, which helps preserve stability where the boundary layer is minimal, and relatively thick and pronounced elsewhere on the shark's body, and in addition, are naturally aligned to the flow direction. The reduction in eddies, which translates to reduction in drag, also means a reduction in the
noise of eddies, which is critical to the success of being an oceanic hunter.