Because it was intended to be flown solo most of the time it came factory-supplied with a relatively low powered engine, to reduce both the aircraft's cost and weight.
[1] In writing about the Hercules, reviewer Andre Cliche explained the engine choice, "Because most people usually fly alone in their two-seater, it makes for a well balanced single seater with peppy performance, low fuel burn and longer range.
However, when comes the time to carry an occasional passenger, its two-seater capacity far outweighs its anemic performance with two people aboard.
"[1] The Hercules was designed to comply with the US FAR 103 Ultralight Vehicles rules when flown as a single-seater, including the category's maximum empty weight of 254 lb (115 kg).
It features a cable-braced hang glider-style high-wing, weight-shift controls, a two-seats-in-tandem open cockpit, tricycle landing gear and a single engine in pusher configuration.