As I recall, the DS cast a pall over the future and made things harder for the jedi in general. As it takes but a moment to pull a/many triggers, the element of surprise coupled w/a moments hesitation is more than enough to do even a jedi (especially a distracted one) in.
As to Anakin's fall, he had already fallen pretty far by the last movie. Since several years have passed between AOTC and RoTJ, it's not so surprising that he'd fall so "quickly". But that "Nooooo..." at the end was sadly pathetic.
Now, I want you to remember that no bastard ever won a war by dying for his country. He won it by making the other poor, dumb bastard die for his country.---Patton
There is no room in this country for hyphenated Americanism.---Teddy Roosevelt
I never forget a face, but in your case I'll make an exception.---Groucho
And if you all get killed, I'll piss on your graves.---Shaman Urdnot
How would you like to own a little bit of my foot in your ass.---Red Foreman