The 8x speed limit on slim optical drives is caused by the much more delicate mechanical construction.
There is no fun in producing 5,25" ODD due to profits close to zero.
Also, demand is decreasing due to medialess distribution is getting more widespread, and (advanced) customers start using network players instead of handling optical discs.
There is some small demand for optical drives, basically to install software and the occasional backup copy. So, ditching the no-profit production of half-height drives in favour of the slim ones sounds like a good business decision for the few remaining ODD producers.
And the customers? As long as they still shut up and pay, all is fine.