Yes, I concede my description of John Constantine was reductive. But notice how your highlight of his best moments don't extend beyond, I think, Garth Ennis' run. Hellblazer had been suffering a slow death for a long time now, and many of things you (and I) admired in the series had long disappeared: JC was more and more a magical thunderbolt-throwing guy (Carey's run), his proletarian roots were being neglected (was Constantine fucking around with a union strike in 'Scab' ever explained?) in favour of silly time-travelling stories, the intelligent political commentary of Delano was turned into a parody with Milligan's Tory/Sid Vicious's ghost two-parter, and for all the talk about his aging in real time, well, he seemed pretty built last I checked Bisley's artwork. And as a fan of Milligan, I'm sad such awful writing came from his pen, that he was the one adding the final nail on the coffin.
I can't lament the end of the series too much, JC really needed to be put to rest. What's sad is that his mismanagement will continue in DC's watered down version. He deserves better than that.