The key selling point of a top-tier journal is not onlt that the content is more important, rather, their standards for publishing in general are much higher. Of course one criteria is impact, but arguably the most important is the level at which the peer review is done. I have heard of papers requiring 3 or 4 new experiments to please reviewers in Cell/Nature.
What difference does going-the-extra-mile in due diligence have on a paper's citation rate? I doubt little if any. People cite publications relevant to their work, regardless of how many replicates that cited paper used or how many supplementary figures there are. But i have no evidence to back any of that up, just speculation :)