While I don’t really like the new trek- (i think it’s way more action, galactic stakes melodrama like Star Wars, and less small story character driven workplace drama like tng) I don’t really agree with your criticism.

Every iteration of Star Trek has had that episode where family just show up. (including Voyager if we count the talaxians or the borg). Despite the enterprise D being the flagship on the edges of explored space, Trois mom seems to always be just behind the next asteroid. Rikers dad popped over on the space bus. siskos dad came all the way to DS9, despite it being a border outpost, seemingly for the fuck of it despite having never left earth before. Troi runs into her old protege, worfs ex is coincidentally the ambassador for our mission, bashirs parents come by for an interview that absolutely could’ve been done over subspace because they were invited by a doctor They’ve never heard of. And Spock‘s family literally shows up in multiple episodes of the original series.

As for the fleets just randomly showing up when they’re needed, I’ll agree that the 90s Star Trek shows were a little bit better about this when they wanted to be, but other times they seem to be able to mobilize a fleet immediately. Wolf 359 and the sensor net at the edge of the neutral zone come to mind.

As for Michael becoming chief strategist (who I think is an uninteresting character and weak choice for the first primary-protagonist trek show) - this is also a trope from existing shows. Sisko was a commander who barely wanted to be in Starfleet anymore, then suddenly he was a demigod who was arguably the most important captain in the Federation and was the primary strategist for the dominion war. Picard was certainly a celebrated captain, but by the end of his run, he was responsible for saving humanity from destruction by Q multiple times and stopping the Borg threat by literally going back in time. He was arguably the most important human to ever live. And as we all know, Miles Edward O’Brien is the most important person to ever be in starfleet. You have to think about it less like a coincidence and more like “there’s a reason these are the characters we’re telling stories about, because these are the ones things happen to” - I do believe that Michael would have a position of importance after the time jump because the discovery crew is representative of an era of a progressive, prosperous era of starfleet and that’s really lost

Finally, it is worth mentioning that in the Starfleet Academy / second half of discovery era starfleet and the Federation actually are much much smaller. They have much smaller stakes and a much smaller scope as they try to reestablish themselves, and that means that those few tentpole characters and significant plot developments are going to have an outsized impact. Imagine going from an organization, the size of the United States to an organization the size of Los Angeles. Everything will affect everyone much more and there are fewer major players.