But what if I had not yet satisfied a minimum stay requirement? In that case I wouldn't be permitted to change the ticket. What if I had someone else travelling with me on a companion ticket? What if the final return flight is now oversold, so I wouldn't be able to re-purchase a seat on the flight I'm already on? What if the client who I need to return to visit insists on purchasing me the ticket? There are a lot of potential problems that may arise by messing with the original ticket. It's much simpler just to buy a new one.

Of course the discussion is really somewhat academic. I'll buy whatever tickets I need to travel when and where I need to. It's not my intention to circumvent any rules.