If Creo included multibody parts they wouldn't be able to charge extra for the "Advanced Assembly" module. I was shown the functionality in SolidWorks and realised that all the skeleton model and copy geometry complexity could be eliminated, along with a £1000 a year to PTC to maintain the Advanced Assemble extension.
Multibody in SW and skeleton modeling in Creo are not directly comparable. Yes, they both are top down design tools, but skeletons with copy & publish geometry features give so much more flexibility. I'm confident that I win enough business and save enough time to justify the expense of AAX many times over.
I've had projects that I only accepted on the condition that the client allow us to use Creo instead of SW because I didn't think we could meet their aggressive schedule without Creo's skeleton modeling tools.