I'm even more cynical; most software from large organisations is bad because it was never designed for the user, it was designed to make the product manager's career advance.
Two factors:
- middle management do not have contact with either customers or shareholders. They report to managers, and only have managers reporting to them. They're insulated from the actual consequences of their decisions.
- the only way to get recognised for promotion is to create change. Any change. Doesn't matter if it's bad (blame can be shifted), it just needs to be noticed.
If a feature of the product hasn't changed for a long time (because it works for the user), it becomes more of a target for changing. If it changed recently, it creates less impact if it changes again, so isn't a good target. So the product becomes worse over time, not better.