Why did Russell and Whitehead’s type theory seem too cumbersome to many mathematicians?

Bertrand Russell and Alfred North Whitehead’s theory of types, as presented in Principia Mathematica, was considered cumbersome by many mathematicians and logicians for several key reasons:

• Complexity of the Ramified Hierarchy: To address the "vicious circle principle"—the concern that objects defined by quantifiers including the object itself lead to paradoxes—Russell and Whitehead created a "ramified" theory of types. This structure significantly complicated the hierarchy of higher-order objects, making the system extraordinarily difficult to understand.12
• The Axiom of Reducibility: Because the ramified hierarchy was so restrictive, it hindered the derivation of standard mathematics. To compensate, the authors were forced to introduce the axiom of reducibility, a special assumption that forced a partial collapse of the hierarchy. This was widely viewed as an ad hoc addition rather than a fundamental logical truth.12
• Alternative Methods: Many mathematicians found more practical ways to avoid Russell’s paradox. They preferred systems like Zermelo-Fraenkel set theory or the Neumann-Gödel-Bernays set theory, which were perceived as more efficient and better suited for mathematical practice.3