Advertising and branding were considered to be crude and base. If the product was likely to stay in the packaging and to be kept on your person or in your home and especially if you were aiming your product at the "upper classes" and more broadly to women then best leave it off or at least minimise it. That's why older stuff is more illustrative in general.
Having the end user do the companies advertising for them is a brilliant, if long fought coup. Basically, putting the label on the outside for all to see. It's also why so much advertising is about the company rather than the actual product. Cool by association.
Can you imagine a victorian or edwardian dude walking around with NIKE balzoned across his chest.
Well that's my story and I'm sticking to it.