What is the importance of Leviticus 19:19? Leviticus 19:19 states


  "'Keep my decrees. "'Do not mate different kinds of animals. "'Do not plant your field with two kinds of seed. "'Do not wear clothing woven of two kinds of material."


What is the importance of including these rules? I know some of the dietary laws of the Old Testament are there for practical reasons, such as preventing disease. Is there a similar practical explanation for the inclusion of these laws? Or perhaps a more symbolic reason for their inclusion?

I notice this verse is mention in the question here, but I am not asking should we or should we not follow such rules, but rather why such laws are present.
The point was to give a concrete definition of "holiness" - namely that God was "set apart," i.e. holy, and God wanted his people to be "set apart" from the other nations. 

These vestigal practices mainly were a symbol of a greater concept - that as God's chosen people, they were to be different / separate from everyone else.

The opposite of holiness is syncretism - mixing in religious practices from outside Israel into the worship of YHWH.  He would often say of himself "I am a jealous God." He would not share his glory with any other.