What a pain in the ass.
The problem is not the Theravada, but it is the Mahayana and the assumption it has built into its very structure of holding itself as being superior and as being the arbiter of all things Buddhists. It has constructed the towering edifice of the bodhisattva path, an impossibly complex path, claiming of itself the greatest nobility and anything else is, compared to that, of a considerably lesser standing (to understate it). Whatever insights that various Mahayanists have brought forth over the ages, as they have confronted the human condition in terms of anicca, dukkha, anatta and paticcasamuppada, those insight get all too easily lost in the dualistic bodhisattva construct that really runs counter to the better impulses of the Buddha's teachings.
The Theravada does not need the Mahayana, but if one is so inclined there is no reason not to study whatever aspect of the Mahayana that might grab one's fancy. There are things to be found that really are quite interesting and useful, but I strongly reject any implication - directly or indirectly - that the Theravada must measure itself in Mahayana terms or against the Mahayana. And that is the problem with the Mahayana structure, it tends force that sort of comparison by its self proclaimed superiority.
This being is bound to samsara, kamma is his means for going beyond. -- SN I, 38.
“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?” HPatDH p.723