Zombie Apocalypse hates you. It wants you to become one of the half-eaten undead, the only logical explanation given a weapon set that includes the useless Molotov Cocktails.
Yes, everyone loves to see a fat zombie waddle around the screen, slowly burning to his second death. However, considering the time it takes to throw a Molotov, they are not a power-up. In fact, they could be one of the worst dual-analog shooter weapons ever devised.