In a previous thread a few months ago, AvatarLee posted a few pics of why it's not as easy as we seem to think it is.
The main reason is the direction to the current pin...
Meaning if WGT were to put a pin location someplace that they did not take pictures of, there would be no proper angle to line up the putt.
In effect, you may be in many positions where you are putting across your screen. without being able to look down the line of the putt.
Maybe in the future WGT will take this into account and shoot pics at potential different pin positions?...not sure, due to the amount of pics needed and possibly time constraints to get them taken.