Because the universe has not been around long enough for us to see objects much farther away than a few billion light years, and with the exception of a few thousand quasars, most galaxies are very faint making them hard to detect at great distances. The Hubble can see individual galaxies with a 10 hour time exposure, out to a 'redshift' of 3 or so, but the kinds of objects it is seeing are still pretty bright compared to nearby small galaxies like the Magellanic Clouds. Even if the universe were 50 billion years old, we would probably not be able to see much more than we do, because it takes a lot of luminosity for a galaxy to be seen as an individual over such distances, and this is what limits even the biggest telescopes in what they can see. Also, because of the redshift, a bright optical galaxy nearby will have its spectrum shifted into the infrared region of the spectrum, and you have to design telescopes differently to be sensitive to infrared light than to optical light. The universe 'hides' distant galaxies by shifting their light out of the normal operating bandpass of the telescope you ar using to study nearby galaxies.