Perhaps - but they had greatly improved pitch stability by 1905,I would go more along the lines of trying to keep weight/drag down and also maybe partly a throwback to starting out on sand - where wheels would not have been good
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By the time they were flying at Huffman in 1905 they could have incorporated wheels and still used the catapult launch but maybe they were more interested in the pure flight characteristics/aerodynamics/stability etc ... whatever the reason -I would have thought it would have been written down somewhere !