I kind of understand the the immediate gut reaction but I can't help but feel people might be over critical on the size. Just to put it in perspective the death star is bigger, they built the second one in about 5 years, and they can move and fly through hyperspace. People tend to overlook the size because they are a bit used to it and it uses the term "base" but in a practical sense it is no different than a giant battleship.
The name "Mega" is dumb though.