I wouldn’t say I’d hate the prequels, but I agree with you that the whole Jedi ethos that George intended in the prequels is inhuman in many ways. When Yoda tells Anakin “mourn them do not. Miss them do not,” George intended for Yoda to be right in saying that.
Except it’s not. In that scene, Yoda’s in a situation where Anakin is giving almost no information, to the point where Yoda literally needs to complete his sentences for him. If Anakin’s only gonna give him vague information, Yoda can only give generalities. And Yoda speaks in riddles.
So, with regards to the part about “rejoicing for those around you who transform into the force”, that’s simply Yoda’s way of saying “when you’re sad, try to remember the good times you had together”. This is also fair advice. He’s not telling Anakin “how dare you mourn or be sad instead of laughing! Bad Anakin! Start dancing and celebrating! Now!”
He’s telling Anakin to cherish the moments he had with that person that’s about to die, which will, in turn help him accept that inevitability, come to the conclusion that they had a good run. Instead of pulling back from these fears and this pain, he should face them head on and accept that it’s happening.
It’s very general advice, but it’s good advice.
I mean, they hold a funeral for Qui-Gon in which they’re allowed to mourn. Obi-Wan mourned for both Qui-Gon and Satine, Tiplee mourned Tiplar, right after their deaths. Hell, Yoda also mourns the Jedi that die during Order 66 and Padme’s death. He allows himself to feel the pain of Anakin’s loss in AOTC and kinda “mourns” for it too. There’s literally a funeral for the Jedi that die in the attack on the temple in The Clone Wars in which they’re allowed to mourn.
This scene is a perfect showcase of how the Jedi deal with loss.
As I’ve said like several times, the only reason the Jedi come across as inhuman is both flat dialogue and the fact that Lucas never develops any of the Jedi characters besides the ones that come across as “exceptional” (Yoda, Obi-Wan, and Qui-Gon, who’s held up on this pedestal as “the one good Jedi” because he receives the most development outside Obi and Yoda). They’re just flat generic good guys, allowing the audience to project whatever they want on them. You can twist Mace Windu from “stern Jedi Knight” to “total asshole dickhead who hates Anakin” because he doesn’t have much screentime or development in the prequels and because of that it’s easy to take everything he says and does in the least charitable way possible. Mace is fed up with the Chancellor grabbing power and is wary of Anakin because he’s explosive, unpredictable and doesn’t have a full grasp on his emotions? “Actually you see he hates Anakin because he thinks he’s the real chosen one! What an asshole!”