I would agree. DR should be considered in light of multiple attacks. For example, my remixed fighter is capable of making not less than 6 attacks per round at level 20. If 5 of those attacks land, the monk is spared 100 damage; that's the equivalent of 2/3 of a heal spell.

Too, in high-op games, DR is just the last link in the chain of your overall damage mitigation strategy, which should include action denial, battlefield control, tactical placement, immunities, miss chance, armor class/spell resistance/saving throws, and finally damage reduction/energy resistance. The monk has the convenience of having DR "in the can" and not needing to go buy it from an (overpriced) item or feat or beg it from an allied spellcaster.