It's because evolution theory is wrong and there are not just numerous missing links...whole chains are missing. This has been well known in paleontology for over 60 years yet hardly ever admitted in textbooks.
"Now, after over 120 years of the most extensive and painstaking geological exploration of every continent and ocean bottom, the picture is infinitely more vivid and complete than it was in 1859. Formations have been discovered containing hundreds of billions of fossils and our museums now are filled with over 100 million fossils of 250,000 different species. The availability of this profusion of hard scientific data should permit objective investigators to determine if Darwin was on the right track.
What is the picture which the fossils have given us? ... The gaps between major groups of organisms have been growing even wider and more undeniable. They can no longer be ignored or rationalized away with appeals to imperfection of the fossil record."
Luther Sunderland, Darwin's Enigma (1988), Fossils and Other Problems, 4th edition, Master Books, p. 9 [2][3]"
"Darwin himself, ... prophesied that future generations of paleontologists would fill in these gaps by diligent search ...
One hundred and twenty years of paleontological research later, it has become abundantly clear that the fossil record will not confirm this part of Darwin's predictions. Nor is the problem a miserably poor record. The fossil record simply shows that this prediction is wrong.
The observation that species are amazingly conservative and static entities throughout long periods of time has all the qualities of the emperor's new clothes: everyone knew it but preferred to ignore it. Paleontologists, faced with a recalcitrant record obstinately refusing to yield Darwin's predicted pattern, simply looked the other way."
Niles Eldredge & Ian Tattersall, 'The Myths of Human Evolution', 1982, p. 45-46 [4]"
""Modern apes, for instance, seem to have sprung out of nowhere. They have no yesterday, no fossil record. And the true origin of modern humans--of upright, naked, toolmaking, big-brained beings--is, if we are to be honest with ourselves, an equally mysterious matter." (Lyall Watson (anthropologist), 'The Water People,' Science Digest, Vol 90, May 1982, pg. 44) [24]
"No fossil or other physical evidence directly connects man to ape." — Gliedman, John. "Miracle Mutations." SCIENCE DIGEST 90 (February 1982): 90-96. [25][26]"
"Fossil evidence of human evolutionary history is fragmentary and open to various interpretations. Fossil evidence of chimpanzee evolution is absent altogether". Henry Gee, “Return to the Planet of the Apes,” Nature, Vol. 412, 12 July 2001, p. 131. [31]
“But fossil species remain unchanged throughout most of their history and the record fails to contain a single example of a significant transition.” David S. Woodruff, “Evolution: The Paleobiological View,” Science, Vol. 208, 16 May 1980, p. 716."
http://creationwiki.org/Fossil_record_quotes
http://www.bible.ca/tracks/dp-fosilrecord.htm
Geneticist Dr John Sanford talks on how genomes must degrade over time...not improve as Darwinian evolution asserts...
http://www.youtube.com/watch?v=pJ-4umGkgos
http://www.youtube.com/watch?v=_edD5HOx6Q0