Pope Pius X did not just pull this out of nowhere. He only emphasized what had been taught by the Church from the beginning. Frequent, even daily worthy reception of Communion has always been promoted. Even the Council of Trent addressed this issue. He wrote an encyclical in 1905, Sacra Tridentina. This is the opening paragraph of that Encyclical, which can be found here in its entirety:
ewtn.com/library/curia/cdwfreq.htm
Some other examples:
St. Augustine - Eat every day, that you may gain strength. O Christian Soul, if thou wish to preserve thy beauty, never quit the table of thy heavenly spouse. If you would live forever, eat every day his flesh.
St. Ambrose - He is our daily bread. Why dost thou wish to communicate only at the beginning of the year? Live in such a manner that you may Communicate every day. He who is not fit to communicate every day will not be worthy at the end of a year.
St. John Chrystostom - It is not rashness to approach the altar frequently, but it is rashness to receive unworthily, even once. Each day, let us go in quest of this Heavenly Bread. Feed us, O Lord, with this daily bread. Each day give us this Heavenly Bread.
St. Basil - Daily communion is praiseworthy and useful.
St. Anacletus (Pope) - After the consecration, let us all communicate, unless they wish to be put out of the church, for this is commanded by the apostles, and hence the Holy Roman Church retains this practice.
St. Clement - Any of the faithful who enter the Church to hear the word of God and abstain from Holy Communion, should be put forth as disturbers of the order of the Church.