REAL WORLD! think inside the box

One thing I love being back in school is how I get to think outside of the box. Especially the class I am taking right now, adv 325 under Sean Thompson, has brought new light in my dull life. As an UX Designer, i often rely too much on my left brain to solve the problem. What are some of the reasons that I learn to think inside the box in the real world?

1. Budget
2. Time
3. Expectation
4. Knowing that my idea is going to be turned down
5. Brand Perception
6. Criticism
7. Being not in a position to make an important decision...

but... these all just sounds like bunch of excuses to me. I need to expand my horizon.