I know that great things can come out of groups of people who hate each other, whose anger and dis-ease manifests itself as amazing, powerful music. The same can happen in other situations, such as business partnerships or teams that feed off competition, and trying to better each other, or just general fight-or-flight adrenaline. Also in relationships, violent fiery arguments can coexist with fantastic fiery sex. So "everybody getting along" in a warm fuzzy atmosphere isn't necessarily a prerequisite for success and greatness--but I do believe deep down that a solid, stable foundation relationship between people creates the opportunity for more meaningful greatness.
Maybe farming could be made into a good metaphor: you can rip the hell out of a piece of land and throw buckets of fertilizer on it, and get yourself one mother-f'er of a harvest in one or two years. But what happens after that? The soil is so depleted and dried out that nothing can grow there anymore, not for decades afterwards. And the crops you got are chock full of artificial stimulants and empty calories... high levels of energy but with little lasting benefit. However, if you put more work into it at the beginning and create a sustainable agricultural system, you might have to wait a bit longer for it to come to fruit but when it does you know it can last a long, long time and it will keep supporting itself. People are the same way--if you squeeze yourself dry of all your fire and emotion too fast, it doesn't grow back as quickly, and maybe never at all.
In Remy Zero's case, over the long time they've known each other, they've built a strong, sustainable relationship that makes it through difficult things and provides a basis from which to create freely. They've lived together, fought together, helped each other through life's problems, and yes, I do believe their music is the better for it. In order to really let yourself go, you've got to trust the people into whose arms you're going to fall.