Agreed. Batman is David Fincher while Flash is James Gunn/Sam Raimi/Taika Waititi. DC needs to allow different solo properties to have different tones. Tones should align with the lead's personality as well as the nature of their threats. Some properties fall apart if no one applies humor to the concepts.
In a book like Justice League, reconciling the different tones isn't too hard either. You can show how humorous elements (Flash doing TV commercials) bump into serious elements (the League role and credibility in the political arena).
Would love to see a Jimmy Palmiotti Flash book. I think the JLU episode Flash and Substance laid out a pretty good blueprint for the general tone of The Flash with some serious Reverse Flash stuff thrown in every once in a while. He can also deal with threats that aren't Rogue-related (like delivering organs to the needy or doing more charity work), get into friendships with villains to try to make them better people, etc.
There has to be someone out there who can play up and reconcile these elements of The Flash into a single character: