Aside from the ramblings of Tom King, what are you basing this on?
Years ago, there didn't seem to be a question of Bruce never really having "processed his grief".
That felt more like modern bad writing looking for an easy out as to handle a guy as complex as BVruce/Batman.
Maybe it's just modern writers, I haven't read much from before the 2000s, but considering that we get flashbacks to Bruce's parents dying every few issues I don't think it's odd that people get the impression that Bruce hasn't processed his grief.
You don't have to like it, but that has been Batman for at least the last 10+ years. It's completely fair for readers to see Bruce that way.
But I'm not just talking about comics, Batman in any media who doesn't act like Adam West is too dark and miserable in some people's mind's. The way some people carry on TDK trilogy is as dark as Schindler's List just because Bale's Batman isn't constantly smiling and joking around. DCEU Superman got that treatment too especially in MOS for the same reasons.
Society thinks not overtly happy is the same as miserable and depressed. I've been asked by complete strangers "what's wrong?" and told to "cheer up" for simply having a neutral expression while I wait to check out at a grocery store. Not even looking mad or sad, just a neutral expression. I really think because Batman's more serious than the average MCU hero his darkness has been greatly exaggerated.
Yeah, I already know that and accept it, I'm just venting which is what this whole thread is essentially about. People are allowed to have whatever outlook they want, I'm just saying how I feel about it. You don't have to agree or disagree with me, I'm simply stating that imo Batman isn't as depressed and emotionally stunted as other people say. That's all.
Within the fiction, dressing as a bat was totally sane and worked well (same for all the others who became costumed heroes of the era). He was treated - by the writers and other characters - as completely mentally healthy. There was no indication he hadn't processed his grief in earlier days. He grieved, yes. He still took actions as a result of that horrible event (to fight crime and protect others from the same fate). But he wasn't stuck on it like his is now. He wasn't still living in the family estate - bought a new house as an adult - and I don't think he had big portraits of them. He didn't dwell in the past as much. He had healthy relationships in the present. And Bruce was more Bruce than Brucie in his personal interactions with others.
The big portrait Bruce had in the golden age was of his and Dick. He's very present. He takes breaks and vacations, alone or with Dick and Alfred, goes on dates, hangs out, visits places beyond Bruce Wayne's obligations, eats, and sleeps normally. He does operate during the day, but at night as well.
Your whole argument still seems to be entirely how you define the phrases "emotionally healthy" and "processed grief". Not only that, but because everyone processes grief differently and there are instances where it takes time to manifest itself, it's entirely believable that he would undergo a change like that over time. I don't really see him as being stuck in the past or not having healthy relationships. You have whatever he's got going on with Catwoman, which I don't think would be possible if those statements were true.
I just wish there were more moments of Bruce genuinely enjoying being Batman.
Like… not all the time but sprinkled in.