You're not suppposed to do it according to the manufacturer, but I have been running my wireless mouse (which requires two 'AA' cells, for - I think - about 18 months to a year on four ordinary 'non rechargeable' alkaline cells.
Two are in the mouse, and I replace them with the other two which I charged overnight last time they left the mouse. They give me a comfortable month or so of power.
Batteries certainly ARE a major pain in the backside. Why anyone should choose to run cars on them is a mystery to me. Unfortunately, we're stuck with them. There isn't any alternative if you want a small amount of power in a mobile or handheld device.
I don't think the EESU is likely to ever appear now, but even if it did, woud you really want your kids playing with a 3,500v capacitor containing enough energy to kill them?