I do think that for a special occasion, such as a dinner party as in the OP, most people make an effort with their appearance.
The dress that looked gorgeous in the mirror at home with appropriate shoes might not look so good in stockinged feet!
Prior warning would allow guests to adjust their attire accordingly and/or take alternative footwear - I think you can get mules with a small heel, can't you? 
Vickram Digra's sentence increased rather than decreased.
AIBU To Suggest We Should Call Time On Fireworks?


