Ironically, the people most willing to take oaths are the people who need them least. Because the values imbued in them already resonate with how these people approach life, they don't feel like an additional commitment. Given this adverse selection, I'm curious how effective oaths are when they aren't compulsory. Additionally, if oaths aren't simple and easy to remember, I'm skeptical that they lead to any difference in behavior.
In many ways, oaths are like selling put options. There's no upside when things are going well and they're detrimental when things are going poorly. In the same way that people sell put options to capture a premium, the only reason to sign an agreement with limited or no upside is because it's a prerequisite for something else that you want, like being admitted to the bar or taking political office.