Most importantly, musicians can share their works with others. Other people can see their musical ideas and can try and perform them too. Nuances such as tempo, dynamics (loud soft, sweet, "harsh", are just some examples) can be understood even if the composer is not present and there is no recording to listen to.
Financial benefits can be realized from the sale of sheet music, scoring the piece, arranging the piece for bands, orchestras, etc. Conductors can lead an entire musical ensemble through the piece.
It depends on personal tastes and what it's applied on.
For example: I like Blue. I think Blue is cool! But, I also think red is cool, on a sports car. I think it would have to be Red, but thats what I think. The same with orange. Green for a T-Shirt is cool as well!
Remember that if you want to find out what color someone likes, just ask them. Generally though, Red is considered to be cool for most things.
