My father travelled a lot for business. So much so that he had a massive map covering a wall in our garage. Before heading out he'd put Blu Tack on the various places he intended to visit and planned out the route he'd take. This required a very high contrast representation of roads to assist him in finding routes; especially given he couldn't magnify the map to focus his attention.

Today, people tend use maps differently, they generally use the map to find POIs (with the assistance of search) and then just ask the computer to tell them how to get there (using various prompts). So, it makes sense that the emphasis is no longer on the streets, but the things that happen to be on those streets.

In some respects, the map is an outdated form for data visualisation. It retains usefulness (in part) because automatic routing remains imperfect (especially for walking in urban environments). However, in time these imperfections will be corrected and I suspect maps will be relegated to niche applications and 'advanced' tabs.