The other night Steven and I talked about the state of our respective works-in-progress. I'm nearly done with mine; he's in the middle of a round of heavily transformative edits. We both mentioned issues we have with out work, and one thing that came out was how the issues in question aren't basic stuff like "does this plot make sense?". Instead, they're more like "are the implications of this theme really what we think they are?".
Maybe the problems I'm worrying about are only things that authors with ambition have to worry about. First-world problems, in other words. And when you get to that level, many of those questions tend to have answers that revolve around interpretations, which are subjective. You've gone past the level of whether something is factually good or bad (poor spelling, wretched grammar, incorrect usage, etc.) and into the realm of whether something is aesthetically or subjectively good or bad (realization of ambitions, worldview of the works, etc.).
That's not the worst complaint to have, as far as complaints go. But it can be unsettling to know there is literally no one you can turn to for a definitive answer: yes, this is good; or no, this is not good.
Most people like a definitive Yes or No to a question. "It depends" is the answer they hate the most, because it means they have to think about the problem all over again every single time. What a pain, right? I once read somewhere that the brain evolved to conserve energy, hence its outsized pattern recognition resources: the easier it is to classify a problem as being one of an existing kind, the less energy needed to actually tangle with it. That made sense when we lived in the savannah, and there might be days at a time when the only calories in evidence were whatever ants we could slurp up out of a local anthill. But today?
Anyway, my point is this: Every writer who plays over their head often enough and aggressively enough will eventually end up in territory where their risk-taking exposes them to criticism. If you're receiving that kind of criticism, it's a sign you've made progress.