I just don't see what a writer being less than exemplary has anything at all to do with the executive editor of the company. Unless Didio was forcing Jones at gunpoint to make Jason Todd into a tentacle rape monster, the only fault you can find in him is deciding to hire Jones in the first place. Which is hardly logical; how was he supposed to know that Jones was going to turn Jason Todd into a tentacle rape monster?
Didio was originally going to kill off Nightwing, but then looked at the fanbase and decided that it was a bad decision, and decided to kill Superboy instead -- I actually got the impression that they were going to kill off both of them originally -- which honestly was a much better narrative decision. What's the problem? He saw that he had made a mistake in judgment, admitted as much in numerous statements, and decided to fix it and is still trying to fix it. When was the last time you heard Quesada admit that he make any kind of narrative mistake, even a trivial one?
DC and Didio make a lot of mistakes and is still making a lot of them (Picoult on Wonder Woman = PURE UNSPEAKABLE SHT) but to compare him to Joe Quesada? The brain behind such crowning glories as the Xorneto clusterfrack and Sins Past? At least when Didio screws up big you can blame it on him hiring the wrong writers as the writers seem to be making all the big decisions at DC. What's Quesada's excuse? He's incredibly hands-on in the writing process and almost all of the big, controversial decisions that have been made in Marvel recently have come directly from his noggin.