Now with that said, should parents be able to gripe without repercussions? Absolutely. But griping is not the same as expressing regret, and expressing regret can imply you weren't really up for the job.
Intrinsically, deep down, I feel in complete agreement that you're right about that statement. And then I stop and think "wait, isn't that the very point I was just trying to make above? That something is wrong with this?"
Why do children have to me more important than parents? Why not 'just as important'? Consider: if we had a friend who had a new boyfriend and constantly put the boyfriend's needs above her own saying 'that's just how relationships work, you put their needs above yours, always', we'd have an intervention for that friend. We'd say that's not healthy, that there has to be give and take, that we all have our own needs that are important too.
But make the other side a child and well, now that's just the right way to do things.
I'm not saying that we're wrong for thinking that- I'm saying we should really look at that deeply and figure out if we're sure that it's right. How far is too far? Are we past that point? Maybe our own happiness should sometimes win out over our children's happiness and that's not a monstrous thing.