Кажется, на форуме проскакивало:
Для того, чтобы рендерер не рисовал дорожную разметку на этих участках (“полосочки вдоль дороги”, к сожалению, не владею терминологией).
Но точно не знаю.
The question would be: for what do we (Ukrainian user) need that?
The reason for this complex areas is to simplify voice messages of navigation systems:
If I had area:highway, I can generate only one voice message, for instance: make “U” turn. without area crossing I get in Example (pict) nr. 1. the messages for every node in the crossing: drive staight on / drive left/ drive left/ drive staight on.
From the legal point of view and traffic rules we have still the nodes on the crossing. If somebody need special personalization of navigation system according to the local traffic rules, it is still possible.
With other words, in this example: 4 roadways = 4 junction = 1 junction polygon
RFC area:highway is now in the tagging list:
https://lists.openstreetmap.org/pipermail/tagging/2015-August/026278.html
Please make positive lobbying 
I added one hint for a:h mapping guidelines:
http://wiki.openstreetmap.org/wiki/Proposed_features/area_highway/mapping_guidelines#Paralel_ways
Best regards to all Ukrainian OSM friends!
Marek