One of the most difficult aspects of freelancing is coming up with ideas - especially for travel stories. I can understand a magazine's reluctance to send me somewhere not knowing what I'll write, but how do I know what I'll write until I've been there?
When I was my own editor, I'd pick a place and find my story once I got there. This made it challenging, but it introduced an element of surprise and, I think, verisimilitude. If you go somewhere with an idea in mind, that's what you focus on, blocking out other, often more important stories. Also, you may uncover a lot, but it's in service to a story that's already been written (which is how you learned of it in the first place).
I used to arrive in places unbound by expectations. That's how I found the Cajun Woody Allen in Lafayette, Louisiana; the Dubrovnik sculptor known as Pero Limunada (because he once ran a lemonade stand); the beautiful young woman in Penang whose goal in life was to "upgrade" her husband. No one had written about these people, at least not in English, and I felt a real sense of discovery that gave my stories, I thought, a certain freshness. Now, journeys have to be plotted and planned, objectives stated, sources given, scenes sketched out before they happen. It robs travel of one of its most lauded features (serendipity) and makes it just another predictable, programmed activity. Is this why travel writing is suffering?