text: Hello fellow OSM mapper! :)
  Thank you for the suggestion!
  It would be a good idea, but there are some other details we have to consider:
  Motorways are simple: at least 2*2 lanes, with shoulder lane, without "same level intersection". Acces is limited.
  Trunks are a bit other. A 1+1 lane road can be a trunk (see M2), but there are limitations for "same level intersections" and for acces also.
  Main roads have less access restrictions, and they are toll free for cars. However you have to pay for trunks and motorways.
  
  We do use the idea to tag roads regarding their importance, but we use this in cities (where roads have not always ref number), and sometimes we mark smaller roads as less important, if i.e. the surface is too bad.
  Also I think most users would not understand why it's marked as trunk, if it's not a trunk.
  So sometimes we mark a road as less important (despite the ref number), but we rarely mark it more important, as it is.
  Also you have to consider, that this part is a maxspeed 110 part, with no same level intersection, but near Csór, where the road is also 2*2 lanes wide, and separated, you have several 70 maxspeed, with intersections, which you can't mark as a trunk, as there is crossing traffic. I don't think it's adeqaute to change importance after every couple of kilometres.
  
  I also have to say, that they are planning to develop this road to motorway.
  Also there are plans to create a new road type, maybe called as "elevated speed road" (so not a motorway and not a trunk), where limited intersections, and increased maxspeed will be the main difference to simple main roads (like this new part).
  I think, after this new rule starts, and the suitable roads will be marked, we will also update the newly marked roadparts as trunk, but in the mean time, they will stay simple primary roads.
  In the future, also feel free to contact us through our mailing list: https://groups.google.com/forum/#!forum/openstreetmap-hungary