One of the things to remember about space is, that it is very very big!
This vast size can be both an advantage and disadvantage at the same time:
The disadvantage is that you have to have a huge database of unique content to keep things exciting, dynamic and not too repetative.
The advantage however, is that once you have built a large database of content, you can just use that content over and over again with SMALL variations to quickly develop new star systems and areas of space. In addition, its worth noting that there are, of course, large areas of space with nothing in it.
It would be very easy for the devlopers of STO to create a large and exciting universe, it just depends how much work they want to put into it - and given that space will be the primary playing field for STO, i think they will work very hard to make it interesting.