…and God will be more impressed with us if we’re properly attired.
Okay. Un-huh. Right.
One should dress reasonbly as a sign of respect. Respect to God, to his house of worship and to his people.
Personally, I usually dress minimum business casual....but then, I’m old, and have been dressing that way for decades. Even for a trip to Walmart.
The aim is self-discipline, not to impress God. That's one of the reasons the military - at least when I served - emphasized that one's appearance be "squared away."
Dressing appropriately - for church or any other venue - is the first step in building a positive self-image that carries you forward to greater accomplishments. It also demonstrates a respect for those around you.
It is very easy to ignore this and dress sloppily and I have to work against that tendency myself. But, with church in particular, I find that when I dress nicely - pressed shirt & trousers, shined shoes, perhaps a tie & coat - I pay greater attention to the service and get a lot more out of it.
All of this used to be generally understood. Watch some YouTube videos of street scenes in the '40s, '50s, and even '60s. The fashions change but you don't see a bunch of slobs.