I don't see why everyone suddenly has a problem with this. It's always made perfect sense to me. To generate a beam of light that is powerful enough to kill someone requires enormous amounts of power, more than a simple handheld battery can supply. Modern laser assemblies would have to be carried by a vehicle, and are too large to be anywhere near effective in the field for military applications. Pulse lasers exist, true, and while they are more energy efficient, they still require massive amounts of energy to work.
A handheld laser gun, even 500 years in the future, makes sense to have only a few shots. Lasers aren't going to suddenly require miniscule amounts of power to generate beams strong enough to kill someone. Visible beams at that, where a good portion of the energy lost will be to the visible spectrum. Also, makes sense because if you can hold that shit in your hand, it also makes sense that most of the thing is actually a heat sink. I actually disliked how the captain's pistol recharged itself. It makes no sense whatsoever.