There are several kinds of human-human relations in which dumbing yourself down are good thing. For example, in employee-employer relationship employee usually act dumber than his boss. Many women 'playing dumb' when it seems useful for them, especially when a man pays, and most of sales people doing this all the time.

But in some situations, you will probably hate it and will have an urge to be yourself - not act or adapt at all, and not see other people's acting. But this type of relationships is very hard to find. Usually what we got is a compromises, especially when in the middle age.