You do not have a monthly Vet bill. No one in the neighborhood needs know that you have an unregisterd pet. They do not kill the neighbors cat. (Some neighbors get a little upset at that sort of pet).
They do not 'bark' at night (at least not that I can hear), We can go on vacation without leaving them in someones care. They are not destructive. Turtles mate pretty quietly. No loud carrying on like other species. (Cats)
A few turtles we have, respond to my wife calling them, That is fact, I have seen it from time to time. They also look at you when the food given them is gone, as if to say 'More'?
The Superworms give a fair amount of fight, that seems to excite the turtles, carnivores/omnivores, that they are. 'Prehistoric', is the look they have.
Now isn't that fun to save something 'Prehistoric' in your own (Jurasic Park) back yard?