1. I'm in this with Sloaken, it's about the money. Code artesans won't make it in the real world. I mean, you might get very lucky and have a huge budget and all the time in the world, but unless you count on winning a lottery it's not happening. Deal with it, it's about making money with the code, not vice versa.
2. That one little extra thing you decided by yourself to code turned into 2 bugs, 4 feature requests, missing documentation and a duplicate tool library since another developer / team was working on something similar. In other words: don't go solo.
3. Getting shit done is the number one quality of a developer.
4. This is more towards designers but applies to developers as well: The customers' opinion about our UI/UX comes first, your opinion second.