we know Apples does it, but have anyone ever know of 'why' they do it?
Apple believe in a chuck away society, constant turnover of devices is how they make money - Steve Jobs himself was a big believer in this philosophy. The engineers tried everything they could to provide expand ability to the original Macintosh and Steve stopped them every step of the way - They even tried inserting a 'diagnostic port' into the design that could be hacked as a form of expansion - Steve 'the visionary' stopped it.
In the mean time, the Apple IIGS, which was a great little machine designed by good 'ol Woz, was fitted with a castrated CPU and gained literally no marketing over the Macintosh - And the IIGS allowed for expand ability with proper expansion slots and a great OS.
Somehow, the cMP 4,1/5,1 slipped through the cracks and now Apple would like to put an end to this '10+ year old and still perfectly capable machine' shit.