Apparently, if I’m not wrong, the chin is made of glass, not aluminium like the current iMac. This can be seen from one of the promo videos, in one of the scene you can see the chin is shiny and reflective.I never minded the the chin before, and I don't now, but the missing apple logo means all my attention is just staring at that big aluminum panel. Without it supporting some other visual element, such as speaker perforations or a logo, it becomes its own visual element, & it's not apparent why the design team thought it should be. Strange.