You say, “fancy suits and fancy dresses.” No one is asking anyone to wear the finest money can buy to go to Mass in. A suit or dress would be what is appropriate, something other than the casual.
You may disagree, but IMO, coming to Mass dressed casually is to denigrate the Real Presence even if it doesn’t out and out deny it.
Why would there be no discussion of what is appropriate to wear to Mass 30 or 40 years ago, but now, the “it’s all about me” bunch want to argue about how much they can get away with - no bras, cut-off jeans, “crack-showing” pants, flip-flops, “wife-beater” undershirts? Oh, yes, they are the ones packing the Adoration Chapel. NOT!