This probably takes VERY little time and is more likely done in some people spare time. Its part of the fun. If you dont like them, nothing is making you click on it. I am 51, but I am also an IT person by trade, and a lot of IT professionals are "silly". We play video games, watch Marvel movies, and stuff like that.
Tesla is a tech company, that happens to make cars (and other stuff). This stuff is in the "T" menu that you dont have to access, so it doesnt really effect you. The "They should be doing something better with their time" argument is the same one everyone makes when someone does something they dont like.
I have had people tell me that I should be "doing something better with my time" than playing video games when I want to on the weekend. I dont judge people who go out and party every weekend, I dont want someone judging me because I choose to play video games sometimes.
I will likely never use those games in the tesla, but I dont think it took more than 1-2 people a few man hours to put them in there. It also helps Tesla keep up their "tech bro" appearance that they absolutely have, and is one of the reasons they got off the ground in Nor cal.
TL ; DR
Doesnt hurt anything ,doesnt take a lot of time, is "funny" and light hearted, and is not taking away from anything else.