^
Pretty much agree.
I don't understand the need to downplay Zuko's abuse what Zuko went through was horrific. Also hotheadness has always been a trait of Zuko's, so him still having somewhat of a temper isn't that baffling. Zuko's anger has in fact died down quite a lot but he's a 17-19 year old kid (comic ages) who is running a nation with very little help. It's a massively stressful job espeically for one so young.
As for Zuko being emotionally inmature. I disagree heavily with this. Zuko doesn't really have any of the traits of someone who is emotionally immature.
1. Emotionally immature people are egocentric
Zuko can be selfish at times. However Zuko has shown from a very early age and in the series his self that he has a good regard for other people's feelings and desires. This was shown in Zuko alone in the flashbacks where he felt empathy for his Uncle over losing Lu Ten. We see this in The Cave of the two lovers when he empathises with Song. We see this during this time with Jet where he declines joining his group knowing how Jet would feel about it if he ever found out that he was a firebender and on top of that the son of the Fire Lord. We see this when he uses firebending to make Jin happy and is happy that she is happy. We see this with Aang in TFBM. We see this with Sokka in TBR. We see this with Katara in TSR.
2. Emotionally immature people have trouble with commitment
We know this one is definitely not true. Zuko is great at commitment. He spent three years non-stop looking for the Avatar. At least two years looking for his mother and spent 67 years both redeeming himself and his nation.
3. Emotionally immature people have a tendency to blame others
This is also not something that Zuko does. Zuko is very much someone who places all blame onto himself whether he's at fault or not. The only time I can think of where he placed the blame on another person was Iroh while he was back in the Fire Nation and Iroh was in jail.
Zuko though mostly blames everything on himself. He blamed himself for being a failure. He blamed himself for being scarred and banished until he finally realised who was actually to blame. He blamed himself for the betrayal of his Uncle, at no point did he blame Azula for this or anyone else. he blamed himself for keeping the fact of the war meeting from the Gaang. He blamed himself for how he's rightfully treating both Ozai and Azula. Also in "The beach" episode he admitted that he was angry at no one but himself.
4. Emotionally immature people have dependent relationships
This is also not something that is true of Zuko. Zuko is actually a very indepedant person who tries to do nearly everything on his own. Depending on people is actually something that Zuko is still learning to do. He always had his Uncle during the three years he was banished and after but he never really apprecicated his Uncle and everything his Uncle did for him until he returned home and realised the huge mistake he had made. We see in the comics though that Zuko still has trouble depending on other people and tries to do everything on his own which often leads to trouble.
5. Emotionally immature people are irresponsible with money
While this one is a lot harder to really know since we never really see Zuko in the position of handling money, however it's doubtful that he would be bad with money. Zuko would have to be quite responsible with money espeically after becoming Fire Lord at the time that he did. I see Zuko as the type of Fire Lord who wants to be involved in everything espeically with anything in regards of them helping the other nations rebuild.
So Zuko doesn't really fit someone who is emotionally immature.
In fact and I know I'm going to get a lot of arguments against this but it's actually Azula shows the most traits of someone who is emotionally immature. Azula has traits 1, 3 and 4. This isn't a slight against her though, it's actually understandable.
Lightning bending can be taught to anyone, it's the same with metalbending and bloodbending (maybe I should go with healing instead). Anyone can learn it, it's about whether they have the skill and the means to pull it off.
I'm going to put forward a really unpopular opinion but I don't see Zuko ever generating lightning. I just don't think it's for him, kind of like how metalbending isn't for Aang. I actually see Zuko coming across a whole new specialised skill, either one he makes up or one that has been lost throughout the ages.
Anything is pretty much possible though with Zuko since the Fire Nation was pretty much omitted from LOK and while we did see Zuko and even saw him fight briefly, plot needed for him to lose. I really wished we got to see more of the fire Nation after the war.