The two main reasons are 1) the proximity to the black hole at the center of the galaxy would mean a lot of radiation, and 2) the larger number of supernovae closer to the system, would both be catastrophic to planets capable of sustaining life.
Here's some more about Galactic Habitable Zones.
The two main reasons are 1) the proximity to the black hole at the center of the galaxy would mean a lot of radiation, and 2) the larger number of supernovae closer to the system, would both be catastrophic to planets capable of sustaining life.
Here's some more about Galactic Habitable Zones.