I actually liked the Venom story. It was a decent follow up to the original having Venom wanting revenge on Spider-Man (consequences of past decisions) and it integrated the family metaphor into the superhero plot (MJ's whole motivation in the first place was feeling like she's wasn't pulling her own weight and that was bothering her). So far as MJ hiding the symbiote, I think part of the idea was that she didn't realize it was Venom until it was too late and it sure looked like it was influencing her for its own agenda. I also didn't really see it as evidence that her and Peter's marriage was a questionable decision; MJ made a mistake and, while we're given an understanding how it came about, it's never presented as anything but. Even a solid marriage is going to have off days or times when one partner is bone-headed about something. MJ's sincerely remorseful over this instance and Peter forgives her. In context, they seem pretty functional, all things considered.