I really don't think the problem here is beta testing. Betas are meant to find problems that require extensive testing to be found. Rome 2 problems were so evident and happened so often that it's not like they were there because CA did not notice them because they didn't release an open beta. They knew the problems existed, they just simply didn't have the time and the resources to fix them, not to mention many are probably just unsolvable issues derived to their insistence on relying on an old game engine.