If you look at things going on at the national level today in the US, Turkey, Britain, Russia, China you can see clear influence of global events. The Middle East and Africa clearly influences all the above in major ways and the US withdrawal from involvement there, if even possible (not), will not change that. The economy of China influences the entire world's economy. Look at countries like Switzerland and Canada who have traditionally tried to stay neutral and perhaps internal focussed in some sense, the Canadian economy has been hammered by the drop in commodity prices. The Swiss had to break their traditional banking secrecy due to external pressures. Climate change is affecting pretty much everyone and the risks it presents are almost unprecedented in human history.
EDIT: Look at how quickly a disease can spread to the entire planet. SARS, flu, Ebola...
It's not a question of globalization vs. isolationism. This is a false dichotomy. Rather, each sovereign state should try to look out of the interests of its people, and when they don't see results, the people may hold the government accountable by protest, election, or revolution.
Running a state is an immense task with lots of conflicting goals, but the survival of the state and the welfare of its people ought to be the most important. Sometimes this means more trade, sometimes it means less trade, sometimes it means a domestically-focused governance, and sometimes it means geopolitical machinations (if human history is any indication).
[1] https://en.wikipedia.org/wiki/Portuguese_Empire [2] https://en.wikipedia.org/wiki/Spanish_Empire [3] https://en.wikipedia.org/wiki/French_colonial_empire [4] https://en.wikipedia.org/wiki/Scramble_for_Africa [5] https://en.wikipedia.org/wiki/Silk_Road [6] https://en.wikipedia.org/wiki/Crusades [7] https://en.wikipedia.org/wiki/Suez_Canal [8] https://en.wikipedia.org/wiki/Russo-Persian_War_(1826%E2%80%... [9] https://en.wikipedia.org/wiki/Anglo-Persian_Oil_Company [10] https://en.wikipedia.org/wiki/Partitioning_of_the_Ottoman_Em... [11] https://en.wikipedia.org/wiki/Anglo-Soviet_invasion_of_Iran