The problem with bullet-proof vests is that, they aren't actually bullet proof. Instead, they carry a rating for what they are tested to stop.

Typical concealable soft armor works fine against handgun rounds (up to what they're rated to stop), but rifle rounds zip right though. For rifle rounds you need hard plates, which are expensive, heavy, and not easy to conceal. Even then it's not an easy choice; there are different rating for rifle plates as well, standalone vs. soft-armor backed plates, different sizes, different shapes for the front/back sides of vests, and so on. All of which come with their own set of requirements for proper care/maintenance to prevent degradation or failure.

That's not even getting into the legal side of things. In some states civilian ownership of body armor is illegal, in other states it's legal but with a list of caveats and restrictions.

So, when it comes down to it, one has to decide for themselves what they feel they might want/need based on their situation. Body armor can be a useful thing to own, but it isn't the "one size fits all" solution that people often think it is.