First, I'll define manipulation for myself so that any following discussion is clear:
In this post, manipulation is an optimal (though not necessarily completely optimal) use of leverage to influence others.
Is using leverage wrong? Well that's situational, and one can manipulate others in a mutually beneficial manner, such as making a trade. (Your item serves as your leverage, and you trade it in order to attain another item, which is more useful to you. Thus, you have used your leverage in a more optimal manner than keeping it, and your item is what influenced the other person to give you theirs.) Of course, we all know of more malevolent forms of manipulation, but I think that with a definition made as such, it is a neutral thing.
That said, the de facto (colloquial) definition may vary to make it necessarily more negative or (rarely if ever) more positive.
TL;DR
depends on one's definition thereof