Just Talk To The Animals...
Having always been a lover of our non-human friends, the most obvious reason would be to help animals with their problems.
I could settle minor spats between parrots, tell naughty bully cats to mind their own Ps and Qs, find out why a horse is fighting over the corral fence with it's neighbor...
Just imagine listening to a pig tell you about how it was sold to some human who had no clue that it was going to get rather large, since it was a miniature pig.
That poor piggy would tell me about it's family feeding him some weird diet they were told to feed him to keep him from growing "too" much. The pig knows that he will be half starved, get sick and die at an early age.
Speaking with a pig in oinks, could save it's life.
If the pig could tell me his problem, then I would tell his family what piggies really need to eat. I could also tell them that the piggy said it is having emotional issues not being allowed to play outside, and that it was worried about tearing up their carpet and furniture, if he's not allowed to play outside, and root in the dirt.
After all, that 's what piggiess do, even if they are "miniature pigs."
Say a couple of dogs have a serious problem with a nasty neighbor dog, and they can't play outside in peace while their Mom and Dad are gone all day to work.
Well, without someone to tell Mom & Dad, what their poor dog is facing everyday, that poor dog may end up in the pound for barking all day, just to tell the other dog to "Bug off."
I would tell Mom or Dad what the problem is so they can make things better, and will know it really isn't their sweet little woofer's fault at all.
Say some kindly older man has a few stray cats he took in, and he continues to allow them to run loose, because he thinks that they will be miserable indoors.
The cats tell me that they are only going outside because they think he wants them to that. They want to please him, but, they tell me that they would really be happier living indoors, so they don't have to fight, or run from some really dangerous coyote that wanted to eat them.
Just as humans have all kinds of issues, so do animals. Only they have more difficulty getting through to us humans, telling us exactly what their issues may be.
If they have an obvious injury, of course that is easy to diagnose, and maybe not terribly difficult to repair, but just letting the animal know what you are about to do can be a bit more of a problem, especially if you happen to be a veterinarian who the poor creature doesn't even know from Adam, or Rover, or Pal, or whoever.