It's not only a matter of value. Good lenses will yield better acuity across the frame and in the corners better than kit lenses. The same is true of bokeh, since good lenses often have more diaphragm blades. And then, there's build quality, which means a longer-lasting lens; as well as weather-sealing, low light capability, resistance to dust penetration (in the case of internal focusing lenses). There are also other advantages, but that should be enough.
Bodies, on the other hand, become obsolete (from a value standpoint) almost as fast as they are released, and barring dramatic advances in sensors, processing engines and features, there's really no reason to spend more money on a body than you actually need.