Jesus wore sandals, he probably always wore teh most poorest of robes. We know from the Gospels that teh Holy Family were by no means wealthy.
Frankly, as long as its modest, ie. no excessive clevage and nothign so short you can see what the person had for breakfast if they bend over, I odnt’ care, and honestly, I dont’ thing God does either. At least they came to church!
Of course, then there’s the issue of the poor. Who determiens what is “dressed up”? Do teh parishes get a fashion committee? My family were friends with a family that were dirt poor, and their kids wore their school uniforms to mass because those were the “fanciest” clothing they had, but it was second hand and tattered. Know one knows why someon is wearing jeans and a tee to Church, they might not be able to fork out for a decent set of glad rags.
But really, where I grew up, you’d be looking at a public faint if you showed up to Mass in the middle of summer dressed like you were going to some kind of high class funeral.
Its all starting to sound a little too snooty to me, no wonder Catholics are accused of snobbery!