It is in a nation's interest to protect it's industries. Often, developing nations with large, cheap labor forces are able to undercut manufacturers in richer countries. It's necessary for developed nations to protect their manufacturing sectors to keep domestic unemployment down. Protectionism is good for a nation's stability and the people's welfare.
When it comes to governments, the well being of their own people should be the first priority. The easiest way to do that is through bountiful employment. While protectionist measures may limit consumer choice, the overall benefit to the nation's individual economy is worth that loss of choice on an individual level.