had to say about the minis, which can no longer be upgraded with more RAM and the top model of which is a dual CPU machine, slower than the quad-CPU 2012 mini it replaced:
Lower performance, more expensive RAM, reduced storage capacity, worse repairability. Apple's product management has done everything short of cancelling the Mini to kill it.
And there was no need. With the same form factor, they had plenty of room to use SODIMMs. They could have handled a quad-core i7 without thermal problems.