God Who Creates Evil - Brakhot 11

"'[Blessed art Thou] who formest light and createst darkness'. Let him say rather: 'Who formest light and createst brightness'? — We keep the language of the Scripture. If that is so, [what of the next words in the text], Who makest peace and createst evil: do we repeat them as they are written? It is written 'evil' and we say 'all things' as a euphemism."

Isaiah 45:7, which 'Yotzer Or' is based on, is irrevocably altered in the Matbea T'fila. Isaiah says:  "I form the light, and create darkness; I make peace, and create evil; I am the LORD, that doeth all these things." Why are the rabbis uncomfortable with both good and evil coming from God? Why, as the Talmud says, do we change it to a 'euphemism?'