A Warlock does not cast spells (it has invocations, like a monk has ki attacks); neither do fighters, rogues, or barbarians, but given their use of magic-like attacks, a monk may be the best point of comparison. In all cases, classes without spells points (fighters, rogues, barbarians, monks) are still able to make use of Epic Destinies, even those with abilities that cost spell points. In particular, the feat Magical Training is available, as are spell point items, and, for those Epic Destinies that are particularly spell point dependent, such as Draconic Incarnation, spell points are included in the Epic Destiny. If Epic Destinies are to be the justification for giving Warlocks spell points, it is very inconsistent to not give spell points to fighters, rogues, barbarians, and in particular, monks.
Similarly, it does not make sense for a non spell-casting class to directly add power to a spell-casting multi-class. Despite the fact that monks also have magic-like abilities, they do not receive additional ki from multi-classing, say, sorcerer or wizard; neither does a wizard or sorcerer receive more spell points for being a multi-classed monk with magic-like ki attacks. If ease of multi-classing spell casters is to be the justification for giving Warlocks spell points, it is similarly very inconsistent to not give spell points to fighters, rogues, barbarians, and in particular, monks.