If you define a major innovation as one that will have to challenge the established habits; then first and foremost, diffusion of a major innovation requires time, not money. To be understood, desired and finally accepted by the market/society. That’s why all major innovations I can think of started from very niche applications, and then patiently won neighboring niches, one after the other, slowly improving in the process, till they eventually became mainstream, sometime after several decades. This diffusion process generally spans over the lifetime of several companies. One example here: automobiles, around which our cities were ultimately redesigned.
It’s difficult to rewrite history, but had Segway started small as you suggested … it may have been more successful in the long run, as a concept and maybe as a company. To really change the world with some major innovation, starting small and targeting niche applications is the way to go.
After that much hype, of course it was a disappointment. If it had been pitched as a mini version of small electric industrial carts, such as the ones seen in big industrial plants, no one would have been excited about it, but it would have been a minor seller.
This is the second article about the Segway which mentions its durability as a minus.