Look, there's an argument to be made that waiting isn't that bad, and if I'm killed, we lost a high-risk/high-reward power at worst. The risk is really high.
Like, I don't know if all players will press the button for sure, which would cause bad things to happen. I don't know if scum will also press the button, too, of if they think it's worth it just to get free reign on all their own powers (like, what if they are strong enough already?).
I mean, I think if scum were to just let us superpower town without upgrading themselves, that would be game over for them. Which is why it's designed to be so risky, and also designed to be tempered by scum just getting upgraded too.
In the end, I see at worst just more fun if 100% of the players get upgraded, and at best way more fun PLUS crazier powers and hopefully a net gain for town.
What I like about it is that it's all or nothing -- there's disincentive for any faction to only have one player press the button, since it results in negative effects for the entire faction.