I seem to remember that the rough skins of sharks is mainly benefical at low speeds where they tend to swim at 99.5% of the time. Their rare bouts of high speed attacks are limited only to catching food and make up only an extremely small portion of their total energy expenditure. Meaning evolutionary it was more beneficial to them to optimize low speed drag then high speed drag. Of course sport fish like marlin and tuna and dolphins tend to spend much more time at high speeds and have highly polished skins.

Evolutionary result must always be seen in such balancing of things. Birds never suffer from icing on their non-metal wings and therefor don't need special arrangements for de-icing. I have yet to see a winged airplane take off in an almost vertical direction from a complete stand still, a critical ability for a bird to survive. Although rockets (single flight wonders) could be regarded as exceptions to that rule.

Wouter