I think that Mercedes is very unique in that they're the first team by committee to be successful in F1 (correct me if I'm wrong). Previous successful teams had a clearly defined leader who was passionate about success on track, and that winning edge filtered down from the top.
Mercedes is in the sport to sell automobiles, plain and simple. The people running the team are on a knife edge ensuring that the team meets the goals of presenting Mercedes as a powerful brand, and providing on track performance, all while answering to a board of directors answering to public shareholders. It's got to be tricky to get the right message down stream, while appeasing the people upstream.
Now, when it comes to if the war between Hamilton and Rosberg is 'good' or 'bad', that's very difficult to answer. Mercedes' goal is not to win the championship. Their goal is to sell cars. Would winning the championship help? I hope so, or else they'll quit the sport and other manufacturers will notice. However, is winning the championship the ONLY way to sell more cars?
If Nico and Lewis politely alternated 1-2 finishes and wrapped up the championship at Monza, who would watch F1? What would people talk about? We'd just say that Mercedes is a corporate love in that is crushing the competition and taking the fun out of F1.
Instead, we have two drivers who are arguably the best in the world (top two drivers in the WDC sounds like two best in layman's terms) driving the best car in the world, and they're fighting hammer and tongs to prove who is the best.
That's something to talk about. Mercedes isn't taking the fun out of F1, they're putting the edge into top level motor sport! We never know if we're going to see a procession or war! Thank God Mercedes is in F1! Who cares who wins?
(I'm not saying I agree with myself. Just suggesting that Mercedes has lightning in a bottle here, and they'd be daft not to keep it going as long as they can. I also believe that when it comes time to decide who goes where next year, Rosberg and Hamilton will realize the same thing.)