Why does bacteria not have an nucleus?

bacteria , are by definition simple creatures which have a binary division. This is in part due to the fact that it does not have a nucleus like the eucaryotic counterparts. However the reason that it doesn't have a nucleus is because it has a nuclecoid. The only purpose for this organism is to replicate itself., nothing else, so therefore it lacks the more complex organalles such as a vacuole, mitocondria. However it does have a ribosome.

The simple answer would be that it only wishes to replicate so having a nucleous would require a more complex cell division.