I'd argue that were we to take "positive" and "negative" or "compelling," "shallow," "interesting," "intrusive", "restrictive," "uncomfortable" judgments out of the conversation, we'd get to a better definition of what things are without getting into more arguments. The thing we can't seem to get past is the judgment on these games at the same time we are trying to simply define what they heck they are.
Sure. What I'm specifically and objectively referring to is a given games overall feedback loop, which for RPGs is easily identifiable in what its overall procedure of play is. I look at that and try to evaluate how much gameplay occurs before it loops back onto itself, and what, if any, sub-loops emerge as a result of different mechanics and systems.
I also look at whether or not these sub-loops feed into each other as a sign of well-developed integration, which is valuable for increasing the amount of gameplay those loops can sustain before the overall loop feeds back onto itself.
When I then go on to pass a judgement on a game as shallow or uncompelling, I am looking at these loops, seeing very few of them, with little integration and with very little capacity for sustaining themselves before it feeds back into the overall loop, which is just the improv game as I've noted every RPG has at its core.
This is why I've suggested in the past that a good way to think about this perspective is to strip away the Content and Theming of a game, and just look at its bare mechanics. You can have the most intricately detailed and interesting theming and content around, but if the bare mechanics aren't fun on their own, that carries through to the game, and the game won't be near as fun as it could be with something more.
And I'd argue, coming back to the discussion at hand, that that is why PBTA types are so heavily themed and why they don't work as a generic system. The theming is what makes those games, and what makes the Improv Game, the bulk of these games actual gameplay, compelling for their fans.
Nobody is playing Apocalypse World or Masks because Moves are the hot new game mechanic.
Now, this isn't all to say that how I judge a given game is the only way you can do it, nor that the assessment I conclude based on that method is anything but my opinion, but you also cannot try to say that the things I looked at are something else.
The reality of a given games feedback loops are immutable, and like it or not, PBTA games do not have many of them at all. Whether thats a good thing or bad is a matter of taste, and I've spoken to why the G matters for many people.