Epiphany and Corpus Christi vacated their days in the US long ago–almost out of living memory.
I find the mid-week holy days (or even the non-obligatory Monday/Saturday editions) to be enjoyable events. Even without parish festivity–which I think should be required for any “obligation” to take effect for lay parishioners.
In one parish where I served, a few singers commented how nice it was to combine people from the five Masses for the evening liturgy–singing and making music with people across the parish, worshiping with people they ordinarily didn’t see at “their” Mass.
I also think the holy day festivities are important enough to be celebrated across a wider group of laity. So, when mid-week liturgies see twenty or ten percent of the weekend population, it seems we are missing something.