פירוש על ברכות 125:4

This is explained in the Tosefta, that the Sages instituted the wording of "from the world and to the world" [in the blessings in the Beis Hamikdash] in order to teach that this world is nothing compared to the next world, it is as an anteroom before the banquet hall - meaning to say - become used to making blessings in this world, in order to be able to be normalized to the kind of existence that is in the next world, which is described as "totally extended."

And not the simple response "Amen."

And they were not to respond "Amen."