It depends on how you use the list. If you use the list as a pointy-haired boss trying to micromanage somebody's work, that's one thing. But every one of those questions begins a conversation--like you mention with the reply "Why do you say it isn't?"
It's through those conversation that ensures that the best can ideas can come forth. This hinges on the relationship between the reviewer and the reviewee being solid, something that should be worked on long before the design review.
Correct. These are all conversation starters. The goal is improvement through a deep understanding of what you're building and why you're building it the way you are.
Starting a conversation is a wonderful thing, but how you start a conversation matters. Some questions naturally elicit a defensive response, especially when they make the reviewer's opinion a default and force discussion of that - implicitly rejecting the idea that the reviewee's position even deserved consideration. There's simply no excuse for a "question" that embeds a negative assumption about the work under review.
Similarly, solid relationships are well and good, but they shouldn't be abused. Maybe framing a review question badly is OK between co-founders who've known each other for years, though as a fifteen-year participant in an even closer kind of relationship I'd say it matters even then. What's OK once can wear down any relationship if done a thousand times. Even more importantly, that sort of thing just doesn't scale to the weaker relationships that are inevitable in any company larger than will fit into your bedroom. "Why isn't this clear?" will simply poison the tone not only of that review but of the entire relationship. "How can we make this clearer?" or even "Do we need to make this clearer?" would be far better.
As an example, BTW, how do you think the OP might feel about my critique here? Does it seem overly harsh, like I'm putting my opinion above theirs? Do you suppose that it might take some work for us to establish trust, after such a beginning? Yes, it would. Behavior that's OK here on HN would often be seriously inappropriate in the workplace.
It's through those conversation that ensures that the best can ideas can come forth. This hinges on the relationship between the reviewer and the reviewee being solid, something that should be worked on long before the design review.