Poor planning. Lack of diversity in terms of tone. So many titles that it seemed like they were either going for complete market share domination or were just throwing stuff at the wall to see what stuck. As well as some really strange choices in terms of changes that were made to characters and what could stay or go. Like turning the Creeper into an oni. Or making Bart Allen a criminal from the future. Or keeping Barbara Gordon's injury in "The Killing Joke" but taking away her reinvention into Oracle, despite the fact that the reinvention was pretty much the one reason validating "The Killing Joke" even being canon (even Alan Moore thinks it shouldn't be). Or . . . has anyone figured out what DC at that time had against mothers yet? I mean, between them introducing Zeus as Wonder Woman's father and stealing some of Hippolyta's narrative power in that part of the origin, replacing the younger Black Canary who was inspired by her mother with, well, her mother who was hung up on her dead husband and continuing to treat Barry Allen saving the life of his mother as some horrible selfish thing, it feels like they've got some mommy issues.
If they really wanted to do a reboot, they should just pull the pin and do a complete restart aimed at getting kids interested. Maybe take a few lessons from the manga and kids' graphic novel markets. I'd be a bit put out at first, but I'd respect them more in the long run.