The buildings still maintain an advantage over the rough ground in the ease of movement within them and the need to be assaulted. The idea is in areas where heavy fighting/pre-bombardment has been happening is there will be a lot of rubble, imagine the amount created when the side of a building has collapsed! Houses now become almost pill boxes within towns and advancing on them have to be cleverly fought out. The sides will also need to close to a very short range which is representative of streetfighting.

Streets deemed to be void of debris function normally for spotting and so become fire corridors, again similar to streetfighting (you wouldn't send your infantry straight down an open street, you would hug cover unless you are desperate to move swiftly). Another thing is the height difference with buildings, even assuming that there is rubble this does not rule out drawing a line of site to higher stories of a building from outside a built up area.

It is the same as saying there is a wall in front of that hill, most of the hill will still be visible though.

It also makes recon forces more in tune with their function, they will need to actually recon an area before knowing something is there. Finally this gets round the idea of automatically knowing your enemies disposition by purely being able to see them on the tabletop in a built up area and affords them some form of artificial hidden set-up!

If playing with a considerably large town, then areas say towards the rear where there has been less previous fighting/bombardment can still be classed as undamaged. I think this is far more realistic than the undamaged building sitting in the middle of several damaged ones. In such large towns the sides still have options of how to use the buildings (does the defender set up in the damaged buildings towards the fore or set up deeper into the town?).

This would as mention make towns play a lot more like woods where line of site is assumed disrupted even though we can see through it. With the above suggestions towns still have the advantage of roads.

Finally the blanket converge makes more sense in terms of the rules, playing buildings as seen does not seem to fit with the scale. If a tank represents five, how many buildings does a single building represent?