When it comes to advanced mass marketed systems like cell phones, laptops, and hybrid electric cars, the system designers of those products have taken appropriate steps to make them "safe" for uninformed end-user use. In other words, made them "idiot proof". Purely mechanical unregulated ecig battery mods and uninformed end-users is a dicey proposition.
Most consumer battery operated devices are no where near the limit of the batterys operating limits. The high-end flashlights, remote control toys, and advanced e-cigs come to mind as applications that really push the limits of a battery. With the RC toys the device is physically far removed from the person so a mishap is inconsequential. With ecigs a mishap is literally in the persons face.
The biggest danger of an exploding battery or exploding mod is to those uninformed users not aware of the dangers, and of not being aware of how to prevent them. For example, using gear that is incompatible; you shouldn't use a direct battery "hybrid" mod with a common ordinary clearomizer or you'll create a hard short. Most mech mod users aren't aware that the device they are using probably doesn't have adequate venting should a battery vent gas and they are at risk for their rig to explode.
If your mech mod's only vent hole(s) are in the bottom of the tube, and there is no room in the tube for the gas to get around the battery to the vent hole (see pic below), then it likely will explode, because batteries are designed to vent the gas from their top. Mods need for the vent holes to be in the upper 1/3 of the tube, but very few do.
A Beginner's Guide to Your First Mechanical Mod
Battery Basics for Mods: The Definative Battery Guide for Vaping