What about Option #4? We get cross-region travel, but they implement some of the restrictions tied to Free Trial accounts, like being unable to use PF and having to be invited to parties manually (which would significantly mitigate the culture clash issues with things like raiding), and maybe removing access to the marketboard to maintain some regional protectionism.

That way, people from NA, EU, OCE, and JP could visit each other's servers and Data Centres, meet their friends, chat, GPose together, use Duty Finder, etc. All of the benefits, with far fewer of the downsides, and JP could just implement a "No English Client" policy for high-end content if they feel the need to.