dumbing down
noun /ˌdʌmɪŋ ˈdaʊn/
  /ˌdʌmɪŋ ˈdaʊn/
[uncountable] (disapproving)- the process of making something less accurate or educational, and of worse quality, by trying to make it easier for people to understand- Some people criticized the film for its dumbing down of Dickens' novel.