My faucet water isn't nasty tasting. Afterall, I cook with it, rinse my mouth with it, wash my face with it, shower with it, yada yada. I just don't drink it in my gallon a day routine. I assume it also isn't the most contaminated thing in the world.
Before the bottled water/filtered water phase, not sure when it began, my family was putting tap water in old milk gallon containers and thermoses(or whatever). People made do with what they had.
The filtered water/bottled water emphasis is about convenience and also marketing. All sorts of inventions may not be a matter of life or death but are great now that we have it.