I've read in numerous places that he felt really really burnt by being forced to reveal the killer, the shows time being moved all about the scheduling (one way to lose many viewers) and that the show got axed. He/it was not treated well. He'd had it with doing tv. Which is why he insisted on complete creative control this time, enough to walk out on the project until he got exactly what he wanted. He wasn't going to ever put himself in that situation again as it had been too awful a situation the first time round - he'd not forgotten. Nothing to do with series 2 sucking, just the awful way that he and the show was treated by ABC.
I knew all that, Venus. Which is why Lynch's recent confessions about the quality of Season 2 completely floored me - here I was all these years under the impression Lynch was the one believing in his show when all others have given up and was fighting till the last second to get it renewed so he could do more magic, only for him saying now that the show became a piece of s... in Season 2 (basically degrading himself to the level of the masses who turned its back on it when the mystery of Laura's killer was revealed), which means he's retrospectively agreeing it was for the best that the show got put down in '91 (who knows, maybe he even suggested as much to the suits then). I truly feel like we've been suckers for loving something and living with it for 25+ years when its very creator thought/thinks it was crap (well, 2/3 of it, anyway).