I suspect that's not the fault of Slavonic v. Latin...
National churches breed nationalistic converts. The Novus Ordo generation, 20 years from now, will all be attending Spanish Masses in the U.S., as this will be the language that predominates. And with their guitars, drums and other charismatic shenanigans, won't that be wonderful?
Don't think many non-Slavonic speaking people would be drawn to a Slavonic Mass. Same with English. Same with Spanish. Latin cuts across these lines and breeds unity.
Pope John XXIII thought so in Veterum (sp), you know. A masterpiece of work by Ottaviani, which Pope John XXIII put his name to.