The Burn being caused by a magic baby having a tantrum kinda ruined the whole setting for me

The Burn has one of the most classic Star Trek explanations ever—normal human(oid) gains magic powers after being exposed to strange energies. The Burn was several classic Star Trek stories woven together to tell a new tale. It's basically a retelling of the TOS episode Charlie X.

Trauma acting as the trigger for those powers is the most believable part of the Burn. Emotions causing people to react is nothing new. It's how humans operate in real life. Entire wars have been started over the death of a loved one. Emotions acting as a trigger is not new to Star Trek either. It's been used a motivation for dozens of stories.

Star Trek has used the trope dozens of times and several in an almost identical scenario. Such as when Kevin wiped out the Husnock in response to them murdering his wife. Or Riker breaking his promise not to use his Q powers after Wesley was killed. It's a realistic human(oid) response—trauma like the loss of a loved one can trigger a reaction with no bounds.

tantrum

It's really disgusting anyone would refer to the grief and trauma one experiences over the loss of a parent as a "tantrum." Your comment is the very definition of hyperbole.

It seemed to me like it was virtue-signalling and pandering to an audience to increase viewership or profit.

Until people stop seeing minorities as different, then these kind of labels are going to get applied just because they exist. If a cast of non-minorities doesn't raise an eyebrow, then a cast of minorities shouldn't either. Base such labels on the way the characters are written, not because they exist. Stopping bigotry requires not caring about sex, gender, or sexual orientation.

I didn’t really realize at the time how prevalent and dangerous bigotry still was in the U.S

Bigotry is a worldwide issue, not just in the US. The problem is often implicit discrimination, where someone is subconsciously influenced by bigotry and isn't aware they're doing it. It never gets resolved because people get defensive when it's pointed out to them. Stopping it requires prioritizing doing the right thing over being right.

Until SNW used the exact clip of him saying that as archive footage.

That never happened. Discovery was the only show that used a scene from The Cage but it wasn't that clip. If Memory Serves did a "last time on Star Trek Discovery" segment that used clips from that episode. It gave backstory on Talos and Pike's relationship with Vina. The clip of Pike making a sexist comment was not used, and has never been used in any other show to date.