My only complaints...

I don't have problem with both of that you mentioned. A riot could be triggered by something simple. It's just a trigger anyway. The real meat of it should have already been in place.

He wanted to be a stand-up comedian because he wanted to put a happy face to other people. That's why his mother called him "Happy." Of course his mother always want to bring him down, she's a crazy narcistic.

Also, in the end after he realized everything and transformed into the Joker he doesn't want to be a stand-up comedian anymore. Just a comedian in general.

1) Those who were protesting and rioting were job-less. Half of them were good for nothing slackers like the street kids who beat up Arthur in the beginning; they are the ones who don't want to work and are less educated. You will find such people everywhere in any countries.

Idle mind is devil's workshop.

I'm sure you are well educated, civilized and well employed. So its difficult to relate them easily. These guys are arrogant enough, get easily carried away and have all the free time to do something that attract attention. Some of them settle down in life after getting proper jobs/getting married etc. Rest of them are the ones who get driven away into the world of crime.

Both of those comments are right. As for the "revolution" part, I'm guessing that they wanted to make the movie consistent with some themes from the comic books. But yes, a general revolution, with people wearing clown-masks, is far-fetched. As for the "comedian" part, he seemed to have tremendous self-esteem problems, and serious mental conditions, and he knew that he had this "laughing" disorder. He was not so dumb to think that he did not know he was not a good comedian. His desire to be a clown (e.g. entertaining kids) is even a bit of a stretch, but this is not implausible. But to go on stage in front of adults to try to make them laugh is another. And again, perhaps they wanted to link the character to the comic Joker, to whom humor was of import; so they get this dark-comedian thing. But yes, those aspects of the movie are weak (putting aside some interest in adhering to the comic-book themes.)

How do you give it such a near perfect rating while having 2 issues with it?

1) The anger and resentment was building in the background the entire time. Arthur didn't cause the riots or stoke the anger, he just took advantage of the unrest or perhaps accidentally became a rallying cry.

2) Maybe being a clown and later a comedienne, the ability to make others laugh, was a way of seeking acceptance.

No, you are right. The films story is silly and it had enough going on to take you away from your point. It's just a movie, but Batman fans wanted to see it veer away from the DCEU and that's what the movie did. The true DCEU is still The Dark Knight. That one I gave a 10. This one is a 7.5, so I gave it a 7 as it's rated too high.

First... it reminded you of the 80s not just because it was your favorite decade, but because it WAS the greatest decade!

Then... You are right. Arthur was woefully inept as a prospect in stand-up comedy.
But, that's not how he saw himself. You have to remember, he was insane.

The rare time that he laughed (intentionally), it was usually about something the rest of us would find terrible.
He laughed and danced while the policemen were being beaten...
He joked with his former associate (the little guy), after he had just brutally murdered the other associate.
After he murdered DeNiro, he did a little dance for the camera...
The nurse he killed and walked her bloody footprints down the hall at the end (ending in another little dance)?

The idea of killing, or just scaring, was funny to him.

And it became annoying to him that others didn't share his humor.

Firstly, I thought this wasn't in the DC universe. I thought maybe it was going to be a guy in our world who wanted to become the Joker from the comics, or something like that.

1. These DC movies are annoying with their stupid focus on removing themselves from the comics, but wanting to have similar outcomes. Gotham wasn't "Gotham" enough for people to go insane enough abandon life and create a Joker cult.

Joker appeared to take place in a New York kind of setting and that would never happen as people are too comfortable. You would need grinding poverty, drugs, and a dark broken creepy city for that to happen. Tim Burton did a more cartoon version of that.

2. Joker is an angry person who finds terrible things funny. He wants to get up on stage and make people uncomfortable. It's a passive-aggressive thing with him. He doesn't really want to be a comedian.

Later, in the comics, he does ironic "funny" things that kill people, because he hates people.