There really isn't a good reason to collaborate. Honestly. Collaboration is messy, a lot of work, and frustrating most of the time. The number of pianists I've fired in my lifetime out of frustration is more than triple the number of romantic relationships I've had.
So then why are we forced to collaborate throughout our careers?
Simple: Collaboration makes you better. And who doesn't want to get better?
I have a friend and colleague, Bronson Foster, recently contract me for a gig. Now, aside from Bronson being an excellent emerging conductor, he is also a bit of a collaboration nut. I mean, I guess he has to be because he's a conductor...but he loves it.
Not me. No way. I would much rather play in an ensemble (which I understand is collaborating) or play solo than work with a small number of people. The scheduling is always a nightmare and the personality conflicts are enough to drive anyone crazy.
But I want to be a great bassoonist, just as Mr. Foster wants to be a great conductor. So, I get myself to a place where collaborating is a priority.
But again, why collaborate if you dislike it so much?
Because, my friends, learning to like something is the best way get better at it. Want to get better at listening to pitch? Work with a pianist. Want to get better at lyricism? Work with a lot of chamber players? Want to get better at being a damned good musician? Work in small groups.
And don't we all want to be better?