And give up the performance in brightness of 123's in a Surefire? No. A Surefire e1e with the KL1 led will give you one hour at full output (similar to a 2d Maglite) and three or four more hours at a diminishing output. This is using a single 123 Lithium.

Standardize most everything else to AA or AAA, sure. Everything else EDC or BOB is standardized around them or is only a nice extra. Even the flashlights use 3 AAA's to run leds. Several places make AA battery units to run a USB charger for cell phones & PDA's