When I shutdown I would like a shutdown sig to be sent to my database and then continue once it gets a successful response. No one wants that to just be killed because that would cause data loss.
When I shutdown I want my filesystem synced so things mid-write don't experience data loss.
The problem is badly written scripts that keeps sending a "one more min" response. But you could override that if you actually cared instead of just whining.
But as you wrote, If someone really cares, they would fix it.
PS: But what usually gets me about these 90s waits whenever I get them is that the message does not say which thing (unit, etc) is the issue. THAT is something worth criticising.
If it is taking 5 mins for my db to respond with "success" then either fix the db or switch it.
That's not systemd's fault that the database is rubbish.
Just because you decided to kill the database while it was still in use, that's your fault.