It seems like one of the driving factors of most of the Crises/Flashpoints/etc is to 'clean up' the status of the DCU; continuity gaffes, the 'is there/ isn't there' aspect of MultiHyperVerse, and generally just getting all their ducks in a row. Most of these events (objectively speaking) have only served to add to the confusion.
Many of the things that caused a need for CoIE happened as a result of the natural progression of the titles; things happened in various story arcs, and over time the inconsistencies became so many that drastic measures were called for. Enter Crisis on Infinite Earths. And it worked... for a time. LoSH notwithstanding (which should be excluded, being as heavily invested in time travel as it is), the post-CoIE universe for the most part fit together and made sense. But as the old glitches in the system returned, DC decided another patch was required; Zero Hour. Since then, we've had at least half a dozen re-castings of the DCU; each trying to correct the faults of the previous one, while usually just adding new ones requiring a future adjustment. Wouldn't it be easier (although, I admit, not as profitable) to fix these in situ? Each title could fix the anomalies it caused, and as long as the channels keep open communication and respect each others' plot trajectories, we could have harmony in the multiverse.
EDIT: In reading that over, it occured to me... DCU is the Matrix!