When I changed my 1979 Raleigh Comp GS from the old Campy Nuvo Record square tapers to a RaceFace Cadence 2 piece crank with the external cups, it convinced me that square tapers are dead.
If there is something odd about your bike that you have to have a certain chainline, then square tapers will let you get there. But then you have to play with spindle lengths, offsets and how different crank sets sit differently on that spindle. Not to mention the few different types of square taper.
It's just so much simpler to be two piece or a octalink or ISIS type crank and BB that engineered and standardized their fit so you don't have to worry about the many things you do with square tapers.
Yes this is all IMO. If any have an affinity for square tapers, that's fine with me.