To test my theory.... does everyone remember the knock knock joke that goes... knock knock. Who's there? Banana. Banana who? Knock knock. Who's there? Banana... etc etc etc... until Knock knock. Who's there? Orange. Orange who? Orangechu glad I didn't say banana?
Do you remember how funny that was the first time you heard it? I thought it was ingenious. But now, if someone says it, as soon as they say banana, you know the punch line, and it's neer going to be as funny sa the first time you heard it. So it's not so much cynicism, as just conditioning that makes people hard to impress. And granted, it doesn't apply to every situation, some things never lose their appeal... but for jsut everyday, run of the mill kinda things....