Most defenders need mobility as part of their defense. Practics does not advocate searching when defending is possible. But somebody has to gather the kids or shepherd the household to a safe location. I think most home defenders plan on being bare-footed during an emergency. The very nature of an invasion is that it disturbs the environment it is violating--your home. A clean kitchen floor may not stay clean. A clear stairwell may become cluttered. Once the home has been breached the defender can no longer be certain of its physical condition. Further, the defender may be forced outside the home. Footwear must not be an afterthought. Bedroom slippers are not stable enough for the sliding, pivoting, high-stepping which is likely foot movement during a defense of an invaded home. Many would-be defenders will claim that a little pain won't deter them during an actual criminal encounter. Its certainly true that adrenaline and focus will minimize the distraction of minor pain but it is also true that defenders may not be under the influence of adrenaline throughout the entire episode, and not all pain is minor. If you have to cross a kitchen floor coated in shattered glass, don't expect that you will be able to tough-it-out.
Keep a pair of shoes by your bed that are easy to get on (hopefully with only one-hand), can be secured without laces, have soft but sufficiently thick soles, are quiet on all surfaces, and don't slip on wet surfaces (crepe soles don't handle liquids well). Firearms are not a cure-all for anything, they're just a tool. So are shoes. Make certain that you have the tools you need in the unlikely event that you are forced to defend your home's occupants.