Baron! Baron! Dwarves want baron fixed!
There is a workaround for the baron (which is not to say it shouldn't be bug-fixed by Toady, but still, if you want one, you can do it).
When you've met the wealth and export criteria and a dwarven caravan/liaison show up, prevent your leader from meeting with the liaison until the caravan has
left the map entirely. (Draft the mayor into the military, or lock him in a room far from the liaison, or lock the liaison into a room far from the mayor, or all of the above.) Once the last merchant has left the map (one of the guards might stay behind and become a "Friendly" instead of a "Merchant", but it still works), then you can allow the liaison and the mayor to meet. The liaison will let you become a barony and appoint a baron(ess).
This still won't enable any other nobles to show up though, like the Tax Collector, or
And dungeon master!
... that.
And annoying soap/washing spam too.
Workaround: make sure all soap is stored in the hospital coffers. Any soap that's not in the hospital should be forbidden.
And probably some other stuff I cannot think of right now.
Inability to use crutches (leg-loss dwarves are permanent invalids).
Inability to use plaster correctly.
Planted underground crops disappearing just after season change.
No elven/human diplomats.
No wagons in caravans.
I've probably forgotten something important, but those are the major ones for me personally, that I can think of right now.