As someone mentioned with a cop reference, just because they have power and the side of the law on their sides doesn't mean all cops abuse that power.
Pokemon Rangers aren't stealing Pokemon that belong to other trainers, nor are they abusing them and selling them off for a profit. They're far from the likes of the Rocket Gang. In fact, they pretty much just tame a Pokemon and have the ability to have them aid them in any missions they have. As we've seen before, they're usually let back into the wild.
That's true, but it's not like we see the other side (i.e. the law enforcement) beyond the occasional glimpses of Officer Jenny. Granted, they're compensating with the Pokemon Rangers, but they aren't the official countermeasure of Team Rocket (the Global Police is). More a sub branch, but that's how I see it. And the fact is, the villainy aspect is more popular and has more exposure in the anime (even the Team Rocket org as minimal as
that is). Plus the "turning evil" characterization is so chic, in response to Icha's comments.
Anyway, my reason to post is, yes, I know the concept of Rangers and how it's the reverse irony of the Rockets' outright stealing. I'm just focusing on the "using" aspect -- you still
use the Pokemon in both said groups. Not quite like stealing another Trainer's Pokemon with your Poke Balls or harming them as you let them immediately go with the Rangers. However, I think the argument can be made that said Pokemon
could be differently exploited for the tasks at hand, albeit for short-term and benevolent purposes.
I emphasize could because the moral issue is debatable -- the real debate would,
could be "would the ends justify the means?" for thought. Rangers just removes the negative connotations of the possible exploiting (as far as I'm concerned). That's not a criticism, just a personal observation.
More to the point, I want to say this: that above is my personal opinion of Rangers and I don't care for them. More power to those who do. I just see them differently. And I don't know if this is the place to argue that -- since we're getting off topic.