The resultant part file can be larger in files size than the assembly file but remember, your intended audience only has to open up that one part file. In alot of cases, part files are larger than assembly files and assembly files are never even close to the sum of the referenced part file sizes. Your intended audience of defeatured assemblies don't have to load your assembly file and all it's referenced part files. (Plus all the benefits of the geometry simplification, including usage of video resources).
I hope this helps.