8. Classic Characters M.I.A.
One of the biggest issues fans had with the reboot was that it seemingly erased classic characters from the picture. Undoubtedly the most high profile absence was Wally West, who had taken on the role of the Flash for over a decade, and was arguably the version of the character audiences were most familiar with, owing to his presence on the long-loved Justice League animated series.
And yet, the character went completely missing during the reboot, along with other heroes, like the Question (no, the version we got most definitely isn't Vic Sage), Cassandra Cain, and a whole host of other classic characters - all wiped in the name of keeping things simple. Which is awful, if we're being honest.
Look, it's understandable that DC wanted to make sure audiences didn't get confused, but at what point do you admit that you think your audience is just completely clueless? The concept of there being more than one Flash isn't an inherently difficult one to grasp, nor are some of the other, finer points of the DC mythos. Getting rid of them completely was just a bad move, but one that the company has, however, taken steps to rectify.