clipping planes are there for a few reasons that I am aware of.
Firstly: Memory use. The more stuff viewable in the scene and the more poly's you cram into it the more memory it consumes and the harder your machine has to work. When theings are out of your viewable area, or out of the clip plane the consume a lot less resources. Where as if your clip plane is set to say 99999999999 far and .0000000000000000001 near you might start having some troubles. Though if there is nothing in the scene, there isn't too much to be worried about.

Another thing is for rendering from a camera view. If you have a 35 mm camera placed into the scene you shouldn't be able to get too close into objects. As in real life you can get so close to an object with a 35mm lens and not get defined detail. So it helps with realism in quite a few ways.

One last thing. The clip plane among other things is a value in maya which can go to far high higs, and very small lows. Values like this are meant to be incrementally increased and decreased to optimize render time and performance.