I guess they can't win. If they had not have told you? If you had been running against the clock and heavy traffic? If they closed the check-in in front of you?
The email is probably a standard layout, including the subject line, with the actual amount of time inserted by the computer. So it would show the same subject whether for 5 or 2hrs 55 change of time.
Better than the time I was not informed of the departure time being brought forward by 30 mins. Once by FR and once, amazingly, by VS. I caught both but the FR was by the skin of my teeth and the VS only because friends had to drop me off extra early. Both companies had my email address and neither sent me anything - or apologised. It's the only time I have been cross with VS but not the only time with FR!