Does it mean that a liturgical marriage, with a priest is unnecessary?
Indeed, that used to be the case. However, there were clandestine marriages were the was no evidence the marriage had taken place. Later if the man had his eye on another woman he could claim that the marriage had never taken place. You can imagine what people would have thought of the woman and if there were any children they would be illegitimate. There is no doubt the man would have been believed over the woman.
In the sixteenth century the Council of Trent issued the decree
Tametsi which introduced canonical form. However, to come into force it had to be read out in a parish and only came into force in parishes where it had been read out. This was also the time of the Reformation and there was great upheaval so in some places it had been read out and canonical form was in force and in others it was not.
In 1907 Pope St Pius X issued the decree
Ne Temere which introduced canonical form throughout the entire Church. So, the bridegroom and the bride administer the sacrament to each other. However, to overcome the problem created by clandestine marriages the marriage must be witnessed by an official delegate from the church (usually a priest) and two other witnesses. Canonical form is also required for validity not simply liceity.
There are some canon lawyers who argue we no longer require canonical form. It is only imposed on Catholics. If two non-Catholic Christians were to marry we, i.e. the Catholic Church, would recognise their marriage as a valid, sacramental marriage even though they had not observed canonical form. Marriages are public nowadays, not least to satisfy civil law requirements, so the problem of clandestine marriages no longer exists. Those canon lawyers who say canonical form is no longer required say it is a medicine given for a disease that no longer exists.