Is there value in saying sorry for an historic wrong?

This week Prime Minister Justin Trudeau formally apologized in the House of Commons on the behalf of the Government of Canada for the 1914 Komagata Maru incident. There's more than a bit of irony here, because apologizing for historical wrongs is something Justin Trudeau's father, Pierre Trudeau, refused to do as prime minister. 

Despite that, there are in Canada today many descendants of the people who were turned away on the Komagata Maru and those people still feel the sting of that discrimination and rejection. It has been a stain on their adopted country's history, and they're applauding the formal recognition by Prime Minister Trudeau this week.  

But history is full of incidents and periods for which people with the sensibilities of today can be ashamed. What is the value of such an apology? Does it highlight despicable behaviour that we ought not to forget? Or is it a distraction from the challenges that face us today? Is it something that lets us all move forward with a clearer sense of what is right, or as some say, has it become a convenient political strategy because there are so many things done throughout history that later generations come to reject?