You're making your own counterargument there, of hundreds of millions of laptops out there with worse cooling, SSDs/HDDs aren't dying at epidemic rates and have gotten vastly more reliable. Most laptops probably have less to no airflow going over the SSD than the PS5 because of their thin designs.
NAND in fact prefers operating warmer to a degree, but not the controller. As cool as possible isn't the best for it like other parts, but rather bringing it to an optimal point and not having it go beyond.
There also is some overhead for some amount of heatsink height, the channels going up and down would be preferable. Looks like something like that WD Black with a flush heatsink would fit.
I feel like assuming they just didn't think of heat is going to end up as...You know.