THAAD, PAC-2, PAC-3 normal, PAC-3 new fat, SM normal, SM future fat, ESSM, RAM normal, RAM fat, possible SLAMRAAM range extender motor — all using different motor diameters. Maybe economizing down to, say, three for the sake of interoperability of launch systems?

Or maybe, just maybe there’s a method to the madnss? If you look at the development of the various missiles I’m sure you can figure it out. As for interoperability of the launch systems, I’m sure you’ve heard of the Mk41 VLS? And if you keep interoperability in mind that will give you a clue as to the reason behind PAC-3 MSEs motor.