The writers messed this one up by making Foundation FTL jumps have basically no caveats. In the books ships could only jump to Hyperspace when they are a few days away from the nearest planet, jumps take days to calculate, have lots of error, and can only be reasonably accurate for modest distances.

When you write in “it’s magic and anything can happen” then you start to ask “why not use every ship as a weapon?” or “why not leverage the vault as the obvious galactic-scale superweapon that it is?”