I got started in officiating after receiving a call from my old high school's AD, asking me to give it a try. So I was recruited. When I started doing games, the ref was considered more of an authority figure than now - I find that coaches are more argumentative with officials today, IMO as a way of showing their players that they "support" them. It's a cheap way of trying to bond with their team.
The WHO-TV segment pointing out the time/travel commitment problem is very true in that it discourages officials from advancing in the profession.
Shouts and critiques from the stands are about the same as when I started - there are more split families now though, so lots of times the dads aren't sitting by the moms telling them to be quiet. So the dads are now non-stop. There are more isolated crazies who go "over the line" now. Many more fans are looking down at their cell phones as opposed to yelling about the travel call however.
By far though, the biggest reason for the shortage is the constant disrespect shown to refs by the fans, coaches, administrators - in the stands, on social media, etc. Instead of being "the" authority figure - given the task of trying to ensure the contest is played in an impartial, fair manner by enforcing the rules - officials are considered the "enemy."
Optimistic, energetic new officials get worn down very quickly.
Lots of talkers not enough doers.