[simias]

There's a huge selection bias at play. Back then being recorded was a big deal and quite rare, so what little of it survives to this day was probably not representative of the bulk of how people talked.

Also back then people traveled less (especially in the lower classes) which probably made accents stronger and more easily identifiable. Now it's routine for people of all classes to move to a different part of the country for studies or work, and you have mass media spamming a somewhat "standard" Parisian French across the country.

And speech is still the main interface of communication. In general when people send casual texts they'll try to emulate the spoken language, including nonstandard inflections and spelling changes etc...

If anything on average we probably pay a lot less attention to the written word than we used to because we use it so much more and for much more casual conversation. Few people used to write "wanna grab sumthin 2 eat?" a few decades ago.