Technically speaking, it's a CPU-imposed limitation when used with LPDDR3 modules. See <a href="http://www.intel.com/content/www/us/en/processors/core/7th-gen-core-family-mobile-u-y-processor-lines-datasheet-vol-1.html" rel="nofollow">http://www.intel.com/content/www/us/en/processors/core/7th-g...</a> (See section 2.1.1.3, "LPDDR3 supported memory devices")
Maybe if they optimized for features instead of making it smaller. This is the Pro not the air. People who care about size are going to get the Air. People who get the Pro want Pro features and don't care as much about size and weight.
Isn't a "battery life" discussion really a "battery size/thickness" discussion? Which developer wouldn't accept a 1-2mm thicker laptop in exchange for TB's of RAM?