Our selectors are doing exactly what selectors in every other country are doing. They are picking the best players available to them.
It just happens that some of those players were born overseas, but ended up living over here because their parents brought or sent them here to get the best education, or else they came over in order to further their career by playing county cricket.
No ECB talent scouts are trawling the playing fields of Ireland or South Africa seeking out new recruits. Players come on their own initiative to play in the county game. Kevin Pietersen was just a mediocre off-spinner until English county cricket and his own hard work transformed him into the batsman he became. It was the English system that made him, just as it was an English mother who gave birth to him.
County cricket takes an enormous amount of criticism, but this is one way it definitely does benefit English cricket, and I see no reason whatsoever why our selectors shouldn't pick anyone who's become qualified to play for England as long as they're good enough.
And if that upsets the Aussies, then so much the better. As the great Douglas Jardine showed, once they start obsessively whining that the other team's doing something they consider is outside the spirit of the game (like the captain wearing a Harlequin cap, or getting fast bowlers to bowl the leg theory), they begin to believe and convince themselves they're at a disadvantage and fall apart.