Having seen the look of terror on ALL the animals faces I have ever transported as they were sent up into the hold I don't think I would be taking any pet of mine on a long haul holiday just for the fun of it. It is a scary and alien environment for animals - the extreme noise, smells and darkness can't be fun.
I imagine it will mostly be used by rich people who need their animals as an emotional crutch for themselves without any thought for whether their pet is enjoying it.
As a slightly more amusing aside, I know a captain who once let all of the guide dog for the blind puppies out into the cabin that were in the hold once all the pax had disembarked, and then couldn't get them all back in the cage again.