Ostensibly, these kind of maps imply the time-cost of those obstacles more accurately than a standard map in which as-the-bird-flies distances are more explicitly shown.

It does account for it, but only for one starting point. So the spatial relationship of the objects to each other mean less than the relationship of the objects independently with the starting position (the centre). A user would have to do it multiple times manually, or specify some kind of travelling salesman route to figure out the best way. I think our brains do this more efficiently and quickly but this would really be worth looking into with this new map.

This map isn't for navigating to the place in mind; it's more of a discovery tool based on travel time. Pick a place and then you get a standard geography based map.