I think it depends on what that influence is and how honest it is. For instance there is a lot of influence over people with what types of food are healthy and such, and it's all marketing, because in reality most of those foods are horrible for you. But if your influence is honest and not laden with lies, just the presentation of facts and truth, I think then it is fine :)
Is it "right" for the media to influence people? It's an absolute requirement. How would companies sell anything if they didn't use the media to promote their products? How would we learn what's new and improved and available for purchase? Does effective media cause some to buy things they don't really need? Absolutely. Is that the fault of the media or do you think the customer has a role to play in that decision? I don't care how delicious they can make a Big Mac look on television, normal people have a little self control and can handle input like that.
Now...having said that...I could also talk about abuses when over done or done with the intent to deceive or mislead. There's always two sides to every coin.