I agree with your premise here.
I think Writers had a similar issue, where people were asking questions about research for their writing:
http://meta.writers.stackexchange.com/questions/20/is-it-appropriate-to-ask-questions-on-specialist-knowledge-areashttps://writers.meta.stackexchange.com/questions/20/is-it-appropriate-to-ask-questions-on-specialist-knowledge-areas
In general, I think it's bad to allow questions about something just because you had to travel there to do it. If this was OK then we'd essentially be allowing questions about anything.
IMO the scope of 'travel' is anything to do with the process of moving from one place to another, and topics related to the issues of surviving once you get to that other place. Tacking on "I'm flying to Japan" to a question about nightclubs or churches or something doesn't really seem on topic.