One of the more visible examples of uplifted animals in SF comes from The Planet of the Apes and its franchise. In this case, uplifted apes are used to generate horror and to examine humanity from a distance. Uplifted animals can be included in stories for a variety of reasons.
Coolness is also an important factor to uplifting. Sentient elephants? Cool! The many effects of uplifting might be difficult to keep track of, but that just allows for a more flavorful world.