My long and boring take incoming:

When Nintendo was the top dog, its CEO was Hiroshi Yamauchi, an old-school breed of executive: humble beginning, confident, headstrong and treating the company as his own backyard. Regardless of the pros and cons of that approach, Nintendo experienced great success. However, it was a shock, during the Nintendo 64 era, that the company wasn't at its peak anymore.

Times were changing fast, Yamauchi was old and arranged for a successor. First, he made sure they had another shot: the GameCube. After the console was successfully released, he finally passed the baton to his successor: Satoru Iwata. He was a passionate and capable person, but had a different context: he wasn't the one who made the company grow, a crisis was being faced and... he was (relatively) young. Needless to say, the guy was easy prey for the board of directors and shareholders.

Many people interfered with Nintendo by then, which was slowly, but steady, losing its form. There was no one at the helm that came from below, who grew up without "listening to the market" because there was nothing to listem to. Pride and tradition were considered things from the past, and the company changed its gear to maximum profit. Heavy standardization took off (what people consider the "Mario mandate" is nothing but a reflex of that), so easy mass producing could be done. Focus was solely on what the market indicated that would sell. Disney (which built an empire based on stability) was a clear role model. 

Ultra-protection was a lesson learned, ensuing sophistry (retardation) like: "there's a random guy profiting by selling t-shirts using our characters. If he wasn't around, that would be OUR money". The icing on the cake would be using the same strategy as designer brands: artificial scarcity to create the sense of value, of "selling out", and inducing FOMO. They also prey on menchildren whose mentality would make Chris-chan look like Plato (but that's partly their fault).

Nintendo was never perfect, but had some level of decency and spontaneity that was unfortunately lost, to the point of selling cardboard at a premium (see Labo). The problem is: every major player now have a closet full of skeletons, everyone knows, and they just went "nah, fuck it". People keep buying, they keep falling lower. That's it.