Whether the decision to cancel games was the right decision or wrong decision, I believe it was made for the right reasons. Football is the national game and The Queen was a Patron of the Football Association. They were also in the unenviable position of not being able to see what other sports chose to do, as many other sporting events were waiting to see what football did and how the public responded to it.
At the end of the day we live in a constitutional monarchy. The world has changed so much in the last 70 years and nobody has had the chance to test the nations response to previously accepted protocols when a monarch dies during that time. The death of The Queen is an extremely significant event for the country, regardless of individual beliefs about the rights or wrongs of a monarchy. She was highly respected even amongst many who would not describe themselves as royalist. The FA have erred on the side of caution. With football fans' history of not always showing themselves in the best light that may not be a bad decision, however frustrating it is for the respectful majority.