it's about the rotation and distribution, not to let them act like the 20 elected.
If there would be an attack, in theory, the next replacement candidates need to have a reason to be up to date.
That works with money and rotates from the top to 33% more to top 40 would bring more security.
And yes it would be a tradeoff between efficiency and security. On a larger scale, security matters more than efficiency ( even 40 are pretty efficient, but the risk of 8 doesn't work is also high to loss consensus).
But as far i remember there is some solution from it if witnesses would loss connection to each other from blocktrades.
An example was the US losing its connection to EU.
In that example, it would work.
whatever. looks like you are an idiot