I feel you're being totally unfair on Johnson.
You do realise that the reasons you give for the movie being poor and Johnson not being up to the task where not down to Johnson right?
Johnson delivered his cut which the studio balked at, drafted two editors in (Walter Murch and Mark Goldblatt) who reportedly cut about 20 minutes of the film out (20 minutes of, I suspect, character development) and delivered the hatchet job that got served to us.
Is it a directors fault if a studio suddenly decides to adopt the Fox approach and go for speed over quality, rejects his cut and gets in someone who edits the movie to their wishes?
And anyways, given the time period and stylistic approach of the Rocketeer, why wouldnt Marvel turn to a guy who they know has delivered a similiar movie to how they envisage Cap before?