So basically, a hot shoe on any camera allows the photographer to use additional artificial light sources because, hey, let's face it, the on-board flash can only do so much. :) Aside from being able to use an actual flash unit directly connected to the flash via the hot shoe, with the right accessories, you can also use other flash units (professional studio or otherwise) that are off the camera as well, giving you a wide range of possibilities lighting-wise.
While the presence or absence of the hot shoe does not necessarily measure a camera's worth or a camera's ability to produce the pictures that you'd want, the presence or absence basically tells you it's ability to access additional light options.
While I'm no expert at using a flash and the myriad of accessories you could possibly use with them (like a light dome, bounce cards, inflatable diffusers, etc., ~some of which are kinda worth bupkiss though), I've found that additional light is quite useful when covering events in dark places. It extends your camera's battery life too as you won't have to rely on it to power the on-board flash.
For a more thorough exploration of off-camera flash usage involving battery-powered individual low-cost flash units, try visiting strobist.