By this token, one could also asked why should it matter to call a human a fish.
I don’t see anything in ID theory that entails we should expect to see odd transformations.
Two problems here. First, you seem unsecured about the notion that the transition to whales documented in the fossil record occurred by the type of small steps traversable by a naturalistic pathway, as shown by your use of the adverb fairly. And for good reasons, given that said transition occurred in only 5 millions years and required profound re-engineering. Below is a description by Gunther Bechly of some of the re-engineering that had to take place:
** forelimbs transformed into flippers, reduction of hind limbs and pelvis, tail transformed into fluke (incl. ball vertebra for vertical movement)*
** re-orientation of the foetus for subaquatic birth (tail-first)*
** modification of mammary glands for nursing under water*
** re-organization of kidney tissue for intake of salt water*
** special lung surfactant (lung has to re-expand rapidly upon coming up to the surface)*
** intra-abdominal counter-current heat exchange system (testes are inside the body next to the muscles that generate heat during swimming)*
Second, I’ve never claimed that under ID we should not expect to see a series of fossils documenting the transition to whale.