Ottoman trade income definitely took a hit in the latest trade map revision, though I suppose that mainly affects players that laser-focus on making Constantinople a hub of oriental trade (Hungary/HRE diverting northwards makes it a lot harder to monopolize the home node).
Are Ottomans too strong? Nah.
Should they have an unique disaster? Don't they already?
Is the Ottoman mission tree in need of updates? I would say yes. They have a big tree, but it's severely outdated in terms of what it does. Every mission is basically 'more permanent claims', with a few minor '+x for 10 years' attached. There's no significant 'until end of game' bonus, there's nothing that interacts with monuments, nothing that gives/affects absolutism or administrative efficiency, there's nothing that gives unique CBs or interesting event chains or development in certain areas or interactions with Africa/India, etc, etc. In short: it is boring. There's Australian tribal OPMs that have more interesting mechanics in their mission trees than Ottomans.
What does Ottomans/Anatolia/Arabia need for a more interesting geo-political gameplay experience? A somewhat regularly strong/powerful Persian nation to challenge either Mamlukes or Ottomans. I think PLC and Hungary roll over too easy against Ottomans in most games, and this game has no mechanism of 'defending Europe from Islam', i.e Ottoman attacks Hungary and Austria/Poland/Lithuania/etc defends each other.
Remove historical rivals from Poland/Hungary. Add it via event/mission tree so it happens in like 30-40% of the games at most.