I think the developers can be much smarter in how they do the HDD install. It does NOT take 15 minutes to read 3 or 4 GB from a bluray disk. It takes much less to write it to a hard drive.
I think they should prepare a hard drive install pack, and just do a flat copy from disc to HDD. That would take 1/10th of the time than whatever method they're currently using. There's plenty of room on a bluray disk, so there's no excuse to not use it.