For conferences, sure.
Interviews -- for men - have always been no brown shoes - it's a formal event.
Uh, that word doesn't mean what you think it does.
Formal in terms of dress code implies white tie or morning dress for men. Black tie in 2018 is considered "Formal" enough and except in the most rigorous of circumstances won't raise an eyebrow. In these highly regimented events, tradition would dictate no brown shoes, but again in 2018, evening slippers have evolved to allow more variety and a wider range of acceptable styles.
An interview is a business event. Business events by definition and history have significantly different rules. Far fewer restrictions, particularly in terms of color. One could argue that the TYPE of shoe is more critical in this situation - that oxfords (shoes with laces) are required and that loafers and other slip-ons would be problematic, appearing too casual for the type of event. Even within oxfords, there could be a hierarchy, and sticklers would say that you should stick with either plain oxfords or cap toes, avoiding more casual styles like wingtips, monk straps (obviously no laces but not really a loafer), or saddle shoes.
As for the squared off toes...more of a faux pas in terms of being overly trendy - in other words, those squared off shoes are good for going to the bars, less so for going with a suit.
A suit is a uniform, and there are rules and traditions that define the look. You can push those rules in certain contexts but the more important the event is, the less well suited it is for experimentation.
Regionality also matters as in general the East Coast is going to be more traditional than out west. However, each part of the country has it's own quirks on what would be acceptable and not "boundary pushing" - eg a pair of Bass Weejuns in the Northeast would likely be okay, lighter colors, bow ties, and seersucker in the South (assuming appropriate time of year/weather), and Texas with cowboy boots may not fall outside established norms, even for something like a med school interview
All that said, to the people interviewing, your shoe choice, so long as it is within a standard deviation of the mean, is not going to keep you out of medical school.
