maybe they could of, but if they added them in in the start square would of had to think of some sort of story to go with it, then everyone would be saying how slow the start of the game is just going to loads of different sectors
and if they allowed us to explore them at the end, people might then say, this just dosent make sense, theres nothing to do at the sectors now, why didnt they add them in at the start!?

you just cant please some people:rolleyes2
but of course there are people like yourself who would just go along with being able to explore them when ever in the game