I've mentioned 'AMD' because I only have experience of building systems with AMD compatible motherboards; I have never built an Intel compatible system.
Quite simply, connectivity for motherboards compatible with AMD processors, etc, has to be improved, because in my experience - and also that of people that I know, certain crucial things still do not work properly.
. Memory module slots are too tight
Memory module slots are far too tight. The amount of force required to insert memory modules is absurd, almost to the point where you are risking damaging the motherboard. We've had ZIF (Zero Insertion Force) processors/processor slots for many years already, so why don't we have ZIF memory modules/memory slots?
. SATA and USB ports are too tight
Ports or sockets for SATA drives and USB devices are also far too tight. The amount of force required to connect SATA cables to corresponding ports, and the same applies for connecting USB devices to USB ports, is absurd. Trying to remove them once connected, is even more difficult.
Other ports or sockets are also far too tight, such as case fan headers, USB port headers and CPU fan sockets. Then there are the main power sockets/connectors for the motherboard and CPU. It is still far too difficult to get these power connectors in, again, almost to the point of damaging the motherboard.
Last but not least, is the issue with standoffs that occurs almost invariably. Which is that the screw-threads are stripped, resulting in spinning standoffs that cannot be properly secured. This problem would be solve if standoffs were built-in to the motherboard to begin with. Then it would be a simple matter of inserting them into corresponding slots/holes on the mounting plate.