Well, of course the KISS principle isn't being observed here. Mr. Murphy seems to be chief engineer on projects such as this. As Jeff Cooper said of the OICW a few years ago, tongue-in-cheek, "Now how have we ever managed to get along without that!"
However, as to the issue of batteries, there is a shortening list of vital items that don't require battery power in the modern battlefield. GPS receivers, watches, some scopes, laser rangefinders, communications devices, Satcom receivers, and many other devices all rely on a power supply.
I have no doubt that the OICW operators will be a valuable addition to the firepower options of leaders on the field of battle, just as flamethrower operators and BAR men were in WWII and Stoner men were useful to SEAL platoons in Vietnam. But, not all soldiers will have OICW's, and not every SEAL carried a Stoner 63.
It is interesting that ATK (Alliant), the prime contractor for this project, recently bought Blount's ammo business including Federal cartridge.