Why is the expulsion of the English from France regarded as a blessing for both countries?

Why is the expulsion of the English from France regarded as a blessing for both countries?

The expulsion of the English from France is regarded as a blessing for both countries; had they remained, the superior size and wealth of France would certainly have hindered the development of a separate English national identity, while French national identity was hindered so long as a foreign power occupied so much French territory.