Creating sea routes now, are a way to realms adapt to the shape of the world.
If we consider, IC, that with reconstruction the people will start to trade again, they would try the best way to achieve this, now, if a trader from realm A wanted to trade with realm C, he would prefer to use a safe sea route to realm C, that does not pass through realm B. Why? Many reasons, the realms aren't friends, more taxes to pay, etc.
This is a realm adapting to the shape of the world.
It is logical that people from Riombara would try to create sea routes to Melhed, because they are friendly realms, it would be dangerous for them to pass through Enweil because the have a history of hate towards each other.
Or Sint creating one better route to Thalmarkin that does not move though OG.
The creation of Sea Routes here are logical and an adaptation of the realms to the new island shape. If we, the players, had the power to do it, we would end up doing it, because it is a logical step to adapt and to continue to have a fun island for everyone. But we can't so we have to ask for them.
Even if done slowly (like, when the city reaches a X number of population or the ruler has the option to build a port) it is an adaptation of the realms to the shape of the world.
And like vonGenf said, it is better to do it now that everything is quiet and in a recovery state than when there is war and the nobles can complain about a sea route been created to reach their city.
