Almost everything's built on something that preceeded it. Some steps are big, some are small, but there's always an ongoing effort to improve things. Maybe you only see or care about the big steps, but the little steps add up.
Are you expecting PU companies to regularly 'create something that hasn't existed before'? All new ideas aren't good ones, or greeted with open arms by consumers. 'New' isn't always better. Some offer little, if any advantage over what currently exists. P-Rails just combined what already existed, nothing new there, and I have no interest in them, either do most players. I don't see them as any big breakthru. They certainly haven't revolutionized the PU industry and taken it over. Fluence PU's are just able to standardize the winds of existing PU's, and as long as they require batteries, their appeal will be limited. Both of these PU's are basically rehashes of what's already been done. I don't see either as anything to get excited about at this point. Maybe some fine tuning will make them of more interest to players. varitone switches were a 'new' idea that flopped. I think most players get excited about great tones, not shiny new objects.