I recently heard an old John Oliver comedy routine in which he talked about a product he'd stumbled upon...a floating barbeque grille. He hilariously makes the case that it is nearly impossible to find a rationale for such a product and I have to agree with him. Things like that can make one wonder if in fact we've pretty well invented everything that can be invented.
A famous quote attributed to Charles Holland Duell makes the same case: "Everything that can be invented has been invented". He headed up the Patent Office from 1898 to 1901 so it's not hard to see why he might have felt that way. It was an era of incredible invention which took the world that was largely driven by human and animal power into one in which engines and motors completely changed everything.
It is easy for us to laugh at such stupidity, but I suspect marketers of the future might laugh at the notion that we live in a particularly hard era for new product innovation. In fact, we have many advantages over our ancestors 100+ years ago. First, the range of possibilities is far broader. Not only do we have fields that didn't exist then (such as information technology), but we also have new challenges that they couldn't anticipate. For example, coming up with greener ways to deliver the same or better standard of living.
Second, we have tools at our disposal that they didn't have. Vast data streams provide insight into the consumer mind that Edison couldn't dream of. Of course I'd selfishly point out that tools like conjoint analysis or consumer driven innovation (using tools like our own Idea Mill) further make innovation easier.
The key is to use these tools to drive true innovation. Don't just settle for slight improvements to what already exists....great ideas are out there....