It makes me wonder too. As somebody who has been involved in numerous phases of engineering and product design for a few decades, to me it always begs the question. Believe me, you could pour 2 years of blood, sweat and tears into what you think is the perfect product and within a few months somebody will figure out some mods to make it better. In mass produced products it often boils down to money. You might easily spend a million dollars in R&D, testing, tooling, marketing and packing to produce a line of aquarium pumps. Then, some cool cat analyzes and thinks of an angle you didn't consider.
Management might analyze and consider those improvement but decide it's not worth it to spend the additional money.
At any rate the guy's improvement look ingenious. Definately worth trying. Or, if you're like me, just shell out a few bucks for a bigger/better pump.