You have one short rest per day, which reduces greatly the power of classes like Warlock and Fighter, and every combat is an epic war against huge amount of creatures that drains all of your resources, so in the case of your cleric and wizard short rest won't make them ready for more battles, you might as well just take a long rest.
Combat should drain the character's resources slowly, from encounter to encounter, spells in D&D are not on cool down like DOS.
