Also Star Wars (as was Indiana Jones) is a tribute to 30s and 40s movie westerns and matinee serials - which means simple stories and fast moving adventures.
The last two Star Wars seemed a failure because the bad guys were not clearly defined - what was lacking in the first two Star Wars was a clear black hat wearing villian and it lacked death defying action.
Well Anakin/Darth Vader, as a bad guy, isn't clearly defined viewing the whole series a whole.
Yep. I forget, is Dooku a bad guy? At first, I thought he was the only one to sense Palpatine's plan and act to raise an army to counter it, but evidently I missed some nuance that aligned him with the Sith. As you said, not clearly defined. For that matter, the picture of the Old Republic that Lucas presents in Episodes I & II looks more like a bunch of feuding Somali warlords than anything else. It's almost enough to make you cheer for the Empire.
There's something else missing from the prequels, too: *humor*. The Original Trilogy had Han Solo - a non-boring, non-tedious, non-Jedi character. His charm and humor helped balance out the heavy, serious Jedi component.