Single action, fixed-sight revolvers are intentionally manufactured with overly high front sights. Once you settle on a load you like, you sight the revolver in by filing down the front sight, which raises POI. When POI matches POA, your revolver is sighted in. It's been done like this for over 100 years.
The reason is that POI changes radically with different loads -- especially as bullet weight changes. Changing from a 200 grain bullet to a 255 grain bullet in a .45 Colt, for example, will raise POI a lot. Changing the powder charge will also change POI, but not by as much. Since the manufacturer can't know what load you are going to use, the gun is built with a high enough front sight to handle anything, and you can file it down to suit your load. If it was built with too low of a sight, the only remedy is to weld additional material onto it. That's not a good solution.
Of course, if your gun is printing low and you don't want to file the sight, you can always experiment with loads until you find one that matches your sights. Adding velocity will raise the POI, and switching to a heavier bullet will raise it even more.
Windage adjustment, by the way, is accomplished by turning the barrel in the frame, which requires a gunsmith (for most of us) and may involve removing and repositioning the front sight. A good quality fixed-sight revolver should not need to have the barrel turned -- windage should be on, or close enough, out of the box.
