For the modern shot makers it is not that big of a problem if they miss the position by a few centimeters, they will still make the next shot as long they can see the potting angel.
If you overrun a position in pool, there is a bigger chance to snooker yourself, because of the smaller table.
Position in pool is much less important. That's why it's so common for you to see players sacrifice getting closer to their next ball, and just taking the longer shot. Whereas in snooker, you will often see players passing up slightly tougher shots if they get out of line in favor of playing safe.
As to your last point, how often do you actually see players snooker themselves playing 9 ball?