Because my water fits the kinds of beer I like to brew, brown ales to midnight stouts, I get by with minimal water adjustment. My water is quite hard and a few grams of gypsum and calcium chloride work for me.
I'll occasionally drink an IPA, wheat beer, or saison, but don't want 5-gallons of any of them.
Of course, the nice thing about home brewing is we're each in charge of our brew kettles, so each to his own when it comes to taste.
Brew on!