Why EEE, (comma) rather than EEE. (period) in date formats with unabbreviated months?

This is a completely personal quest, but I'm really wondering why the standard abbreviated Day format is EEE, even when the month isn't abbreviated?

I personally think that EEE. looks aesthetically nicer, and doesn't create any barriers to reading the date.

So I'm just wondering how this happened and hoping to hear from some folks that feel very strongly about it :)

so Mon. January 1st, 2019 vs Mon, January 1st, 2019