Traditionally, a suit is what a grown man wears as everyday clothes--job permitting.
Only during the last century, and more accurately, only for a period of about 60-70 years, tops. Is the suit still the uniform of the workplace today? Arguable.
i agree that oxfords are a better choice for a job interview but men wear suits to many other places than that. in fact, when wearing a suit to a party or a restaurant for dinner, loafers are more appropriate because they help you look like you dressed for the occasion, whereas if one wears cap-toes or wingtips, you look like you came straight from the office.
Depends moreso on the suit than the shoes these days, imo. No need for me to comment on low vamp loafers anymore now, is there? I realize what I hate nearly as much as the low vamp - no heel.