It's a sad day when a brilliant musician leaves the band that made them famous. The band is never the same. Some bands break up (Zeppelin, Nirvana), some bands keep marching on (Pink Floyd), but it's never the same.
But what of "Supergroups"? When you take the best members of multiple bands, why do some flourish and some fail? It's clearly not lack of talent, these supergroups are the MVPs of the music world. Stick the greatest guitarists on the planet together an you get a platinum record, right?
So what is it?
What makes a band "magical" is the quality of their interactions as a group.
When dealing with projects alone (musical, school, business, etc), the only input is skill. Obviously, the skill of the individual is the primary input into this project so that's what determines success or failure.
But when we introduce group dynamics, the formula changes. Who writes the guitar part at the bridge? Do we add a five-minute drum solo? What is the song trying to say? These decisions are made as the result of negotiations between the band members. The term negotiation usually conjures up images of "playing hard ball" and the like, but almost every interaction is a negotiation of some sort. "Should we add a second vocal part to stress these syllables?" is a question that people skills determine the outcome of.
Musical talent and people skills are TWO VERY DIFFERENT SKILL SETS. Some people have one, some have the other but the truly intelligent musician takes the time to develop both skills.
I'd never be in a band with Yngwie Malmsteen, the guy seems like a wanker bent on showing off. Sure, he's got skills, but I'd argue with him just on the principle that he's so pretentious. There's a reason he's a solo artist.
Have you ever played with a guitarist who heard an idea and immediately said "I won't play that. End of discussion."? Aside from making your head want to explode, how do you think this guitarist's personality affects the quality of the music he'll end up writing in a group setting?
Jack White, on the other hand, happens to make great music with every project he touches. He's not the most technically insane guitarist on the planet, but he writes good songs with good musicians. He's able to deal with the people side of a project to get the best music possible.
If you want to make better music, you must work on both MUSIC and PEOPLE skills.
Learn to listen to your band mates and open yourself up to new ideas and directions. Read some books on management or organizational behavior. TRY TO UNDERSTAND YOUR BAND. You'll be rewarded, both in terms of a happier band and a better songwriting process.
(The new song we're currently practicing I had to be convinced to play initially, but now I love it. You only make progress in a band setting by learning how to best utilize your group.)