The idea that nature is free and beautiful is only seen that way because we are the ones with the freedom to come and go from it as we please. Camping is a fun thing to do not because it’s nice to be out in nature, but because we have the freedom to return. Have you tried camping for 30 years? 50 years?
Humans offer consciousness and empathy, which nature does not. You can see these videos of animals like butterflies being released into nature only to fly for a few seconds before being swiped away in the beak of a bird. That “beautiful animal that deserves to be free” would end up a mangled corpse in the wild. You just don’t die of old age.
Males die younger in almost all species (and eaten by their mates in mantids!) because once you’re past reproductive age, your “purpose” in the wild has been served, at which point nature sees you as worthless. On the bright side, it’s also why animals, such as humans, with paternal instincts have less or nonexistent life expectancy gaps between the sexes (women living longer than men is quite a
complicated story)
Obviously, we can’t just start domesticating every animal in existence, but it’s just worth pointing out that the reason we like taking cool-looking or cute wild animals out of nature is to protect it, even if we only subconsciously realize it. If you’ve ever lost a pet, you know the thing you fear most is whether or not “nature will take it’s course.” It’s the same with mantids, to a much lesser extent.
And as for boredom, a pet mantis would pretty much be doing the same things a wild one would, except with much less stress. We get bored because our minds are designed to handle constant stimulation in the form of stress and danger. We should consider ourselves lucky when we feel bored.