No, its tru - most of MP isn't very funny at all, its just that we forget the crap bits and remember the good.
What's most important about Python is that they did it at all, before them there was practically no surreal style comedy, it was all made by men who used to be in the military and were used to entertaining the troops or Victorian variety music hall type stuff. That Python changed the comedy landscape was probably more important than their hit-and-miss show, but that's what you get when you push so far past the boundaries of the times.
Take a look at Spike Milligan's stuff, a lot of that was so weird as to be unwatchable, but the good stuff was great.
Same could be said of every evolution of comedy - in the 80s when Ben Elton and Alexei Sayle were basically shouting "down with Thatcher", they only had some stuff that was funny, but it changed comedy for the better as it settled in. Today, League of Gentlemen or Little Britain's stuff has a lot of crap in it too, but you remember the good sketches.