Nicholas Leifker wrote in response to me:

If it's a characterization problem, mention it once, and only once.
Mentioning it again in response to the author's response causes it to 

[Snip!]

    "I felt the idea that Kasumi was [insert plot element here]
    just didn't get developed convincingly, and left the whole
    fic not working for me as a result."

Harsh, yes, but if it's your honest opinion and you're sharing it with
genuine feeling ... it's good commentary for the author.

At the risk of sounding rude, this is not a good way of looking at it.
This falls under characterization interpretation.

<grin> Which, as you yourself said above, should be mentioned (once) and
then moved on. Though I wasn't necessarily talking about a static
characterization in the example. You could fill in the blank with "going
to be the host of her own traditional Japanese cooking tv show" or
"secretly an alien princess being raised on Earth by her guardian Soun"
or something REALLY strange.

I think Mike Loader summed it up nicely. You can do pretty much anything
as long as you have internal consistency; but if the critic finds holes
in your logic, well, that's definitely a fair catch.

Nightman
Happy New year!