"Doctors" are honored with this title on account of their brilliant exposition and skilful defense of Catholic doctrine.
Most modern theologians today who even mention Saint Thomas usually do so in the context of a need to go beyond his doctrine. The general erroneous assumption is that we have studied, assimilated and implemented his teaching. Why don't the same theologians say the same about the doctrine of other doctors of the Church? This is a theme that is, to my mind, worn out and boring. It would be more interesting and beneficial to promote Thomism, as the Church has consistently done with the doctrine of all of her doctors. By definition it is especially the doctrine of the Doctors that is to be studied profitably for salvation. Why all the redundant warnings of caution? You get the sense that many modern theologians regret that Thomas is a doctor at all.
Of course we should study other thinkers; but first study the clear doctrine of those thinkers who best elucidate the Gospel; and first among them is Saint Thomas. And, sorry to say, I know of no seminary in the world that bases its theological training on the study of the Summa Theologica so that it is patently false to assume that Catholics (even priests) have a firm grounding in the teaching of Saint Thomas.
The four Western greats are Saint Ambrose, Saint Augustine, Saint Jerome and Saint Gregory the Great, declared doctors in 1295 by Pope Boniface VIII. I have yet to hear anyone caution studying them too much!
So, go ahead, study Thomas with out fear. Study Thomas boldly. Promote Thomism unapologetically. Study him even in Lingua Latina, if you dare, and encourage others to do so!
Viva Thomas!