“In that regard, the Oberlanders who became Chasidim are no different than the Yekkes who became Litvaks.”
Um, no. Unless by become Litvak you strictly mean people who started following minhag haGra. If you’re just talking about Yekkes going from being more modern to more yeshivish, that is in no way comparable to a mesorah change.
“How does being a simple erlich Ashkenazic Jew these days fly less than being Chasidic?”
I don’t think Gaon was condoning it, just pointing out the social trend.