Because, when mentioning a monetary value in a US publication, it's always common to show the value in USD next to it.

Well, million euro’s is currently about 1,158,300.00 United States Dollars, so maybe the copy editor looked at the number and didn’t want to offend the sensibilities of their readers .. anyway, the point is, I don’t think this (parentheses) indicates a dumbing down of anything, other than maybe a sleepy editor who didn’t catch its distraction ..