Final answer:
Frank Lloyd Wright believed Frobel's kindergarten curriculum was too structured and he developed the wooden unit block.
Step-by-step explanation:
The person who believed that Frobel's kindergarten curriculum was too structured and developed the wooden unit block was Frank Lloyd Wright. As a child, Wright's mother bought him a set of geometrically shaped educational blocks that he used to draw lines and shapes. These blocks had a significant impact on his future and influenced his architectural designs.