Splitting hares and other species

In the last couple of decades numerous species have been 'split'. That is to say, what was once thought to be a single species has been split into several. The European Brown Hare, which was once thought to be a single species spreading all over Europe, and over most of Africa and Asia, is now believed to comprise at least three species, possibly more, in Europe, and the classification of the hares of Africa and Asia is still being worked out. In South America the situation is even more dynamic, with numerous new species of primate being separated. The reason for these new classifications is largely the advances in DNA studies, but also for some species studies of behaviour such as song and calls. Important as these studies are in demonstrating the existence of discrete populations, I do have some worries, that we are over-emphasising these differences, and that they may not actually represent separate species. Afterall what happens if, just because a bird that is virtually identical in all other respects to another species, but has a diferent song or call and is considered a separate species? Should we apply the same criteria to humans? This would mean that someone speaking a different language would become a different species. And the differences in the DNA of some of the primates, may be no greater than the extremes found in human populations. Language in humans is often a perfectly good barrier to interbreeding, particularly when combined with other cultural separators, but it still does not make the Otrthodox Greeks a separate species from the Muslim Turks. In the rush to split species, we are in danger of losing sightt of the most important factor in conservation, and that is the ecological integrity of an area. Does it matter if two allopatric populations have slightly different DNA, if either one of them will fulfill the same role in an ecosystem? There is talk of splitting the White Wagtail and the Pied Wagtail into two different species -- but if one or the other disappeared, the one remaining would fill the niche in the ecosystem perfectly well. Or am I missing something?