It's very easy to find classics full of "bad" grammar when it comes to the punctuation because it's in fact not bad.

This is wrong for at least four reasons:

1. Incidents of "incorrect" punctuation in classics is due in large part to the role of various punctuation marks changing over time. For example, the semicolon was once used at the end of questions like a question mark. The em-dash was used in earlier modern English for long pauses, but is no longer.

2. "Classics" is a broad category, and they were written for many different purposes and audiences: they should not necessarily be held as paragons of style. If you're trying to write intentionally, and for a large audience, the grammatical use of punctuation is helpful. For example, Emily Dickinson's poems were primarily written for herself, and were highly stylistic. Not a style you'd want to replicate when writing, for example, a newspaper article.

3. There is a punctuation which explicitly denotes a pause: the en-dash. Why use punctuation which has a specific purpose to do the exact same thing?

4. Different dialects use pause in different ways. Just as purely phonetic spelling would be terrible for internationally audiences, purely phonetic spelling would make texts more difficult to understand. You say punctuation rules enforce a class divide. I say they help bridge class divides by giving a common set of rules not based on and particular English.