I understand the concept of company branding. So, of course everyone in the office wearing the chosen "uniform" can be great to solidify identity of THE COMPANY. I absolutely considered this was needed in some companies/offices after I saw one leasing team wearing short-short cut-offs and camisoles/tank tops during the hot summer months, and when asked if they thought this was appropriate, they responded that they did. In my opinion, you may have to mandate a dress code when people don't have any common sense about appropriate image presentation.
That does not mean I LIKE dress codes forced down my throat right down to the number of pieces of jewelry allowed, the one option only type of shoe some policies mandate, and whether or not I can color my hair. Yuck. Those types of rules do evoke my rebellious side!
To the point that dressing a certain way magically instills confidence with your clients, it depends on the market. I can tell you, and I've said it before, I have leased many, many apartments on Saturdays when I was dressed for an afternoon coaching soccer. In fact, I'd say that the more relaxed and confident your Leasing Consultants are in their own abilities to lease, is more important than whether or not they are wearing black suits with white, pink,or lblue shirts. Managers can easily correct poor choices in outfit with their teams in most cases - especially when companies deduct the cost of the "company apparel" from employee paychecks.