http://mangastream.com/read/naruto/72932747/12 (Notices how these go *poof* rather than splatter like water clones?)
Kisame's real sharks don't seem "special" in terms of talking or special abilities but that doesn't mean they don't have their own realm/place of existence. Not every summoned animal we've seen can talk (orochimaru and sasuke's snakes as well as that big Ninken that Kakashi summons have never been shown to talk). As Kakashi said in the very beginning when Pakkun was introduced, he is the most intelligent of the dogs and learned to talk at an early age. So in other words speech isn't a given for a summon. Unlike all the other summons we've seen (which are all relatively important to the plot etc) Kisames sharks are just fodder summon material the same way sasuke and orochimaru's snakes were. They were expendable and were only used in quick battles. Im sure there's a big great white leader shark or something that can talk and use shark missile jutsu somewhere out there. The fact that Kisame's summons go *poof* and vanish means that they come from somewhere (even if its just in the ocean). Also the "realm" of some of these animals can still be reached by regular means, in regards to Pa Toad saying to Naruto that it would take several weeks (or however long ) to reach Mouth Myo on foot... but its faster to reverse summon.
So if Kishi wanted Kisame to summon a bigger shark and have it swallow him then reverse summon it to escape he could've... but he wanted to kill off Kisame. Plain and simple.