Residential buildings can only be upgraded a certain number of times. If they still don't look as tall or as cool as other buildings, it probably means that the Land Value wasn't very high when they were being upgraded and now they're maxed out (the more services and specializations that overlap an area, the more desirable that area is to Sims, and the more luxurious the buildings will look!)
Try moving the buildings out to another part of town and rebuild in the space that they've left. Then you should get more luxurious buildings each time you upgrade.
http://help.ea.com/en/article/building-residential-zones-in-simcity-buildit/
