Ten utterances because they were the only things uttered by God to the people of Israel. If they are not technically commandments then they are statements of truth about the nature of God's laws...inviolate and eternal.
This of course leads us to another question: Why the ten singled-out statements? What makes them so special? Jewish tradition holds that inside of or included in these ten statements is the entire Torah. In other words, the Ten Statements are actually ten categories into which each of the 613 Torah commandments falls.
I would agree with that. As Christ pointed out they can be condensed even further....love the Lord God with all your heart, mind and soul and love your neighbor as yourself. The first five commandments define the behavior that springs from loving God with all our hearts, soul and mind. The last 5 define the behavior the spring from loving our neighbor as ourselves.
All the Torah is summed up in the first two statements:
"I am the L-rd thy G-d." - a call for positive action
"Thou shalt have no other gods before me." - prohibition of certain actions