The saddle has more than one function
- it sets the height of the strings above the fingerboard (string action)
- It sets the scale / vibrating length of the strings, and
- it transmits the acoustic vibration of the strings via the bridge down into the soundboard
To achieve the second of these functions – setting the scale/vibrating length of the strings – it needs to have a relatively sharp front edge and apex. (This cannot be too sharp else it is going to cut the strings).
But to achieve the third of these functions it helps if it has maximum possible contact with the string. If there was only a sharp apex then the contact would be minimal. To get the most contact it is useful to set the slope of the side of the saddle facing the base of the guitar so that as much of it as possible is in contact with the string as it makes its way to the securing holes through the bridge. There is a slight complication : the saddle tends to slope from bass down to treble side whereas the securing holes in the bridge are in line. This means that what you ideally need is a slope from front to back of the saddle which is set to make for the maximum possible contact for EACH string and that means that the angle of the slope will tend to go from relatively shallow at the treble end to relatively steep at the bass end.