You could say the same about Dark Souls 2: 'great game in its own right - why would anyone ever dare question it!'. But it's a needless rehash with less polish and thought compared to what came before.
I'm not a Batman fan in the slightest (apart from maybe Nolan/Bale/Zimmer/Pfister's version), and so it took me a while to bother checking out Asylum. I enjoyed it enough to want to play City, and that became one of my most admired games of last gen, in terms of sheer polish, focus, and precision mechanics (the challenge rooms elevated its combat to something akin to score attack genius).
Origins? I ignored, and will always do so. Not the same dev, so I have no reason to trust 'em. Couldn't give a stuff about half-arsed prequel timelines - especially given how City had the guts to make certain plot events stick (ergo winding back the clock felt pathetically conservative and not at all interesting). Add to that the other points raised by people who sat through it (re starting gear, waste of origin potential, more bugs, etc), and I think it deserves all the criticism it got, and then some.
Can a prequel cash-in by a lesser dev be good 'in its own right', removed out of all context that may otherwise cast it in a less favourable light? Sure, why not. But Asylum and City deserved better, and more. Hopefully, Rocksteady and Arkham Knight will do the IP justice.
