In order to build Damian up they...
Obviously consider the below to have SPOILERS.
I understand they want to make Damian look like a prodigy (outside his social skills, but that wasn't given as a detriment in this movie) but did they seriously have to make the other heroes look like jokes?
Let's start with a more minor example, Nightwing does not come across as Batman's student. He gets bested by Damian without too much difficulty. In Son of Batman, Nightwing bested Damian but at a cost (being cut up pretty badly). You could argue that Nightwing saw himself as fighting a child and held back, but there should be no illusions by this point about who he is facing. Then later Nightwing leaves his back exposed and is almost killed by a group of the Owlmen.
Batman however comes across as a complete newbie. He starts right from the beginning playing catch-up to Damian, missing some pretty easy clues regarding missing children (so much for being the world's greatest detective).
He immediately blames Damian for killing the Dollman even though there's no blade on his weapon, and if it were the Batman most people are familiar with he'd probably be observant enough to notice the other tracks, the wound not matching Damians weapon's capabilities, might even have heard the end of their conversation since his suit is equipped to enhance some senses). So he knows Damian is a bit unstable and not really accepting him as his father, so he gives him more reason for him to push away?
Then every fight Batman is involved in is either close to a draw or he somehow manages to live solely by luck (and I still don't know how he survived infiltrating the Court of Owls but neglecting to take care of his poisoning, he just sort goes into a hallucination and somehow is saved by Nightwing even though the first time he gets picked up by Nightwing the guy's gf takes priority on his ring-tone. The Court wants Batman out of the picture, they weren't ever wavering on whether they could use him or should just eliminate him). Let's also not forget that Damian completely takes down the Batman on his own.
DC used to be fantastic in producing quality animated movies... the key phrase is 'used to be' because the quality has been almost steadily going downhill. I loved Crisis on Two Earths and consider that the highpoint, I was so-so on the two Batman/Superman movies, and saw a lot more potential for Elite, but almost everything past that has just come across as lower and lower budget with scripts to match. I will say I mostly liked Red Hood (though I wish some of the changes from the comic weren't made), and Flashpoint Paradox (though I wish we got to see more of the alternate reality heroes/villains), and thought Assault on Arkham was pretty entertaining, but Throne of Atlantis was terrible, and quite a few of the Justice League movies were mediocre at best.
I'd love to see an Obsidian Age movie made but... with the current crew doing DC animated movies I know I'd be disappointed.