Dominicans don't think of St. Dominic primarily as a founder or exemplar, as a historical figure or icon. He is "our Holy Father Dominic."
But if he is our father, he isn't really ours, in an exclusive sense. His office speaks of God giving St. Dominic to the Church, which is not only what happened, but what has to continue to happen. The Order of Preachers was not founded and does not persist in order to extract from the general population everyone with a sufficiently Dominican spirituality. It exists to focus, to reinforce, and to strengthen the charism of holy preaching.
A charism has two essential parts: it is a gift from God; it is given for the good of the Church. Sometimes the second part gets forgotten, or at least downplayed.
But for Dominicans today to be good children of our Holy Father Dominic -- and to be a good child is to be a faithful image; just ask Our Lord -- we must be directed toward "preaching and the salvation of souls," in the words of the Primitive Constitutions of the Friars. It may be possible to be directed toward some kinds of preaching -- though not the "holy preaching" Dominicans speak of -- without being directed toward the good of others, but if your business is the salvation of souls then you're directed outwards.
And it's this direction that measures the quality of the Dominican's preaching -- which, again, is to be a "holy preaching," a preaching consecrated to God through prayer, study, and community. There are other ways to holiness, certainly, and there are other ways to holy preaching, but the Dominican way is this particular way, a balanced composite that, if each part is maintained, is sure to produce good fruit.