One reason you are seeing fewer measurements is because schools are doing a better job (for the most part) of lining their fields. When I first started doing this (many moons ago), it was a luxury to work a game on a field that was painted instead of being marked with field chalk. And, even the painted fields back then seldom marked the individual yard lines (tick marks); they just marked every 5 yards.
Over time, more schools started marking the individual lines, and now it's a rarity to work on a field that doesn't have them. With the tick marks (provided they are straight), it's a lot easier for us to tell whether or not the line to gain has been reached.
As for "the networks discouraging measurements", I have worked a few high school TV games, and have never been told anything about avoiding measurements by the broadcast folks. However, I don't know what the big boys (NCAA, NFL) have been told by ESPN, ABC, etc.