Still, some travel. There are different kinds of travelers. There is Amartya Sen at Harvard. He has a joint appointment in philosophy and economics. Becker has a joint appointment in sociology and economics.
Some economists travel, however, outside the discipline.
Hirschman is a good example. I do not see him engaging the more topical issues in economics today, a participation that would have enriched the conversation. The vocabulary he uses is better understood by non-economists than by economists. The real trick is to travel and then remain inside the discipline. This is not easy.