Its a naked power play when placed in context, despite how inoccuous it may seem. Commissioners are appointed by the president and confirmed by the senate. They can be fired by the president unilaterally.

This new rule means that the president only have to get one of "his" guys in, and now you can own all of the SEC decisions if you want by just firing any dissenting commissioners.

In the past, that is the sort of norm that would not be broken. We are now in a world where the president trying to fire fed bankers is real, and that is arguably a much, much, more serious norm to have broken. I don't think this administration will have any issues playing to the letter of the law instead of the spirit.

So with this rule change, the effect is that a president only needs one commissioner and a lack of regard for norms to completely control SEC decisions.