I think many fans usually have more patience than they should if they like a particular franchise or comic company at times.
As for Robert Kirkman, I sort of imagine that he feels a bit bitter about Marvel canceling some of his ongoing stabs. From what he typed in some letters columns, he seemed to have sour grapes about IRREDEEMABLE ANT-MAN. That book lasted 12 issues and sales tanked, but perhaps Kirkman was too used to Image's sales threshold. There, 14k a month is awesome. For Marvel, if that's not a MARVEL ADVENTURES book, it's sacked. At the very least, it's not like too many of his creations from MARVEL TEAM-UP or ANT-MAN have been forgotten; Slott & Gage used O'Grady and Crusader a bit in AVENGERS: THE INITIATIVE. In Marvel's defense, Kirkman's MARVEL TEAM-UP was selling below the cancellation range for maybe the last 6-10 issues of it's 25 issue run, and it still lasted until issue #25 so Kirkman could tie up his subplots in it; frankly that was rather generous considering he wasn't one of Bendis' mates like Brain Reed on MS. MARVEL. I have seen far better books than MARVEL TEAM-UP die before issue #25 that had equal or better sales.
(Although, honestly, who would have expected a series about JUBILEE in which the main gist is that Jubilee ISN'T trying to fight crime, but her aunt is, would sell decently, after 2001? C'mon.)
The irony is the last mini Kirkman did for Marvel was DESTROYER for Marvel MAX; there, he averaged about 13k an issue, and for Marvel MAX, that is awesome. Most Marvel MAX titles sell so poorly even at $4 an issue that everyone wonders how they make a profit.
Considering that Kirkman virtually strangled any potential that Vaughan had put into ULTIMATE X-MEN with his some two year run of doom, which was his best selling run of ANYTHING, I can understand some fans not approving of some of his rants. He usually feels that the Big Two rarely employ new ideas and that they don't give new series enough time to build an audience. The problem is the sales threshold for a Big Two book is higher than for anyone else, like Image or Dark Horse. Marvel cans any book that sells 20k or below without an end in sales slippage or something to make up for it, i.e. digest/trade sales ("The RUNAWAYS Clause" basically). For Image, 20k would be terrific for a book. Only SPAWN usually averages about that much.
Honestly, Kirkman's work is usually better with his own Image properties, and if that is where he is happiest, so be it. He has a right to his opinion and perspective. That said, there are times in his letter column he does get a bit too defensive and whatnot; on the other hand, he also will admit mistakes, something few writers do.
I usually enjoyed Kirkman's Marvel work, aside for Ultimate X-Men and MARVEL ZOMBIES, which I tried and didn't get into.
