I find Yes Minister funny now, and I'm too young to have watched when it first aired.
I used to find The Thick of It hilarious but now I find it a depressing reminder of how ludicrous modern politics has become
Yes Minister is a reminder that politics has been ludicrous for a long time, but I think its style is much lighter than The Thick of It.
I watched the entirety of Yes (Prime) Minister relatively recently despite being younger than the show and not British; and found it delightfully entertaining and often surprisingly relevant to contemporary political issues.
The institution yes minister makes fun of has barely changed in 400 years, let alone 40, the jokes on the whole thus remain fresh.