This applies to any airline upgrade;
1. Captain flows and callouts
2. Deeper understanding of systems
3. Deeper understanding of GOM
4. Better decision making for all situations imaginable
5. Command and leadership skills are shown
6. No doubt is given about your abilities to safely operate as a CA with peoples loved ones in the back.

Given this criteria, it is easy to see why upgrading is a "choice" that an individual makes.