The digital crown and the transparency option are already two buttons, one of them also a knob. I tinker enough already with them and sometimes press the transparency/anc one instead of the crown. A third button for power off just opens to more confusion and introduce accidental turn offs...
I think I’m in the large minority here, understandably so: using them for the last 5 days, they have incredibly grown on me. Best headphones I have ever had (not an audiophile myself though). I’m perfectly ok with them not having a power off button, just like the phone, iPad, AppleTV, airpods/pro, etc don’t have a power off button. They are always ready to be awaken (instantly) and used. Want to turn them off? Do the gymnastics button combination, also like with all the gadgets mentioned above.