In Obi-Wan's situation, it was utterly important to remain hidden, and using the Force can attract other Force users. So, by all appearances, Obi-Wan did what Ahsoka did. He cut himself off from the Force so that he wouldn't jeopardize Luke by alerting Vader or the Inquisitorius to their presence.
The main reason for this is due to Kenobi's long stint in hiding. Again, Kenobi has been in hiding for around ten years, slowly diminishing his connection to the Force. While the Force, and people's abilities with it, are hard to define in Star Wars, it remains the case that the Force acts as any other skill does.
Originally Answered: Why didn't Obi-Wan use more force powers when he fought General Grievous? One reason is that Grievous can dodge force attacks. He did so against Shaak Ti and the other Jedi on Coruscant when he wasn't straight up tanking it.
Conclusion. To conclude, Obi-Wan let himself die because he thought he would become more powerful and more useful to Luke as a Force Ghost.
Retrospectively, Obi-Wan stated that the brutality of war had tempered him, but he also said that it had left him "forever wounded" and that's why he never fought for the Rebellion. Obviously, he was busy watching over Luke, but even if he wasn't preoccupied, Obi-Wan wouldn't have joined another war effort.
She also knows Obi-Wan, and she knows him well. Her holographic plea for help, already iconic, will never be the same. She knows Obi-Wan's real name as well as his alias of “Ben.” When Luke comes barging into her cell and says, “I'm here with Ben Kenobi,” Leia jumps off the bunk in an instant.
Master Yoda has risen above all others to claim the top spot as the most powerful Jedi of all time and the true chosen one according to IGN's audience. He won pretty handily as well, as he was victorious in 89,756 of his 95,243 battles and had a win percentage of 94.2%.
Anakin admits to Obi-Wan that he has been arrogant and unappreciative of his training, and apologizes to his master.
Anakin Skywalker ultimately ended up hating Obi-Wan Kenobi for many misguided reasons, but Darth Vader's subconscious response to the Jedi's final declaration of love in the Star Wars prequels shows the real reason he could never forgive him.
As the exchange was made, General Grievous was in a set of blinders that kept him looking straight ahead. Meanwhile, Anakin had to be drug out of the Separatist ship after being tortured by the MagnaGuards' electrostaffs. Thus, the two passed by each other, but were not able to see each other.
He hated the Jedi so much that Grievous even learned to wield lightsabers as a non-Force user, which was incredibly dangerous and usually foolish. And this deep resentment all stems from his upbringing.
A shuttle crash orchestrated by Dooku and pinned on the Jedi mortally wounds Grievous and leads to his reconstruction as a cyborg. The Clone Wars would later suggest that Grievous was denied the right to become a Jedi due to his lack of connection to the Force.
Quite simply, Qui-Gon did not have much training when it came to trying to combat Sith Lords, and at the time, it would have been irresponsible for the Jedi Counsel to spend any additional time concerning a threat that was considered long extinct, especially when you add to the fact that they believed they would be ...
Padawan Windu was trained in the ways of the Force by Jedi Master Cyslin Myr.
Within the Star Wars Legends continuity, Yoda's Jedi instructor was N'Kata Del Gormo, a Hysalrian Jedi Master, according to an in-universe legend.
Darth Vader hated Obi-Wan Kenobi because he hated himself. This started when he thought that Kenobi was the one that poisoned Padmé into turning against Anakin when he turned to the dark side. But the truth was that Anakin was merely projecting his own self-hatred toward Obi-Wan.
It is unclear whether Yoda would be more or less forgiving than Obi-Wan but one thing is certain - the former Grand Master would be ready to treat Anakin as an ally, following the events on the second Death Star. In Star Wars: Revenge of the Sith (2005), Yoda never really lost faith in Anakin in the way Obi-Wan did.
David Porter provides some great philosophical context to why Obi-Wan would not regret leaving Anakin alive, as it was obviously “the will of the Force” that Obi-Wan be unable to finish him off, and “the will of the Force” that Anakin live on to kill Sidious himself in the future.
Yoda found himself overpowered in battle against Darth Sidious, who would become Emperor Palpatine, but his wise retreat gave him time to mentor a new hope before ultimately succumbing to old age and passing into the Living Force on the planet Dagobah.
Darth Vader only learned he had a daughter in Return of the Jedi - but there's no evidence he realized she was Leia before his death and redemption. Darth Vader may have never known Princess Leia was his daughter in Star Wars and never cultivated a relationship with her, even when he was a Force ghost.
In Death Star, it seems the Sith Lord could have discovered Leia's true identity if he'd pursued his hunch. However, Leia's strong-mindedness during Vader's probe denied him the opportunity to discover she was his daughter.
Why does Obi-Wan Kenobi age like that? Because he's not real, and is a fictional character played by different people. You see, Obi-Wan Kenobi is played by Alec Guinness in the original trilogy. Guinness was 62 when he filmed A New Hope, and he died in 2000.