In a such large corpo no one gives a shit about it. It's just a job, to get a paycheck. They all are expendable resources, why to be invested emotionally into the job?
Systems are complicated and hard to keep in your head. Knowledge doesn't always transfer to other teams. Especially over 15 years. Sometimes you don't realize you've made an error.
Most people are emotionally invested because they spent time and energy to build something and don't want it to be for nothing. Most people like to try to do the right thing.