I dissagree somewhat to your Anakin theory. Qui_Gon told Anakin when he was a boy, that in becoming a jedi, it would be very hard, he would have to sacrifice everything. Anakin allready knew fear, and that was the main reason why Mace and Yoda decided against training him, and fear was his key to the dark side. As anakin got older he became more arogant. Anakin knew he was ahead of the other padawans "ability wise", and he would often show it off. Palpatine had a big influence on his training aswell, and was there from the very start of his training, and always giving subjective advice, and Palpatine's shoulder was always there for Anakin to cry on. Obi-wan was constantly reminding him to keep his mind on his mission, but Anakin was always putting is passions above everything else. It was often difficult for Obi-wan to control Anakin. Anakin should have obeyed Obi-wan, and not question his authority. Anakin would not keep to the Jedi code. That was the hardest thing for Obi-wan to control about Anakin. Anakin was simply too old to train as a Jedi, and Obi-wan would not have trained Anakin if it were not for Qui-gons dying wish. I blame Palpatine for Anakins down fall, not Obi-wan or the other jedi. The Jedi did what they have always done in reguards to master and apprentice relationships. The Jedi were bread to serve the Republic, nothing more.

I don't believe the Jedi's ability to use the force had diminished like they thought. I believe Palpatine had a new technique for hiding his dark self from the Jedi. He found a back door around the Jedi sences.

Of coarse this is only my opinion.