I usually found that some rags and matches were among the most reliable kills, especially in previous versions where fire was an easy stunlock, even against fire damage immune skeletons. It reduced loot considerably, but even burnt clothing can be turned into more rags for more kills.
Besides, in most cases I used it just to get to some houses so I could more properly equip myself, imagine my surprise when I found out zombies can make it through fires now.
Still, twas a necessary update I suppose, and the addition of spraycan flamethrowers still make it ridiculously easy to kill even a hulk (just watch out for the ones carrying ammo, or worse, grenades.)
In short: most any problem can be solved with a generous application of BURN THEM ALL.