I think it's important to be both passionate and objective in a situation. I honestly think being overly passionate or overly objective are equally bad. Extreme passion leads to closed-mindedness, which you can see very clearly anywhere on the internet especially. Any video game forum will have its fanboys that will defend certain consoles/titles/companies to the death and will not listen to any factual evidence. This often occurs in political and religious debates as well, which are very heated topics. Views in those two areas are generally pretty solid and unchanging because of how passionate most people are regarding them.
Being too objective isn't necessarily a bad thing, but lacking passion is. Passion is what drives the world; it's how we invent new technology, medicine, art, et cetera. I think being passionate is one of the most important things you can do in life to attain success. Being without passion, without drive, will prevent you from achieving anything at all. Or if you did, you'd be unhappy doing so.
I don't think being passionate and being objective are mutually exclusive. It's entirely possible to maintain a healthy balance of both and I think the key to success is doing just that. And I believe the greatest error in life is being too flat in one specific area.