It is a truism that many in England were opposed to this marriage and thought that Mary should wed an Englishman. The usual course of a royal marriage is to use it for diplomatic ends; thus English kings had long married foreign wives who became their Queen Consorts. There had been exceptions to this pattern lately of course, as Henry VII united the Houses of York and Lancaster by marrying Elizabeth of York, and four out of six of Henry VIII's wives were English. Nevertheless, a foreign spouse for an English monarch was not unusual.
It is also a truism that many in England were opposed to their Queen marrying a Spanish prince of the house of Hapsburg because Spain was an enemy of England. Yet Spain had also lately been an ally of England--Henry VII had arranged the marriage of two sons to Catherine of Aragon for that diplomatic edge. Queen Catherine had been very popular in England--the people loved her generosity, piety and kindness. Therefore, a foreign spouse for an English monarch could be very popular.
I think the crucial difference was the gender of the Monarch. Mary was a woman, and thus would be ruled by her husband once married; her interests would be subservient to his in the normal course. When Mary became the wife of Philip of Spain, many in Parliament and in the country feared that Philip would rule in England. Mary herself would not accept this view of their relationship. The Act for the Marriage of Queen Mary to Philip of Spain carefully spelled out the special relationship between the Queen and her spouse and the limits placed on Philip of Spain. He was not crowned or anointed King of England and although he would be referred to along with Mary on official documents, Mary was the Queen Regnant, the sole Monarch in England; Philip was her King Consort. For instance, Mary used the King's quarters, Philip used the Queen's! (Like Fred MacMurray and Polly Bergen in "Kisses for My President" a movie in which the first woman President of the United States resigns when she gets pregnant! Fred has the frilly First Lady's bedroom while Polly has the masculine President's bedroom.)
The marriage of the Queen of England to an Englishman also posed difficulties and could easily lead to factionalism at Court. One of the most popular candidates had been Edward Courtenay, released from the Tower of London when Mary regained the throne from Lady Jane Grey. Perhaps his involvement in Wyatt's Rebellion demonstrates his unsuitability to reign--he also attempted to marry Elizabeth; neither Mary nor her half-sister trusted him.