HP, inconscient sexim from JKR?

[Laurence]

No: HPFGUIDX 88241

I don't know if this subject has already been talked about (I search 
for sexism, nothing shows) but in this very well documented essay:

http://contraveritas.zephy.net/funstuff/essays/women.htm

Lena F. suggests that the HP books can be considered quite sexist, 
maybe not so much in the portraying of the characters themselves 
(quoi que... see Molly Weasley) but above all from a plot driven 
point ie very often it is women's incompetence which is to blame for 
the advance of the villains and she gives a lot of example of this 
concept, between Bertha Jorkins (pictured totally incompetent, and 
who's a puppet in Voldemort hand), Ginny Weasley too naive to 
recognize Voldemort in the diary, or the mother of Crouch who let an 
assassine loose. 
(go read her essay to understand better what I'm trying resume)

Do you think that we can call sexist a book which plot advances 
through mistakes more often made by women than by men? Could it be 
interesting to inspect this aspect of things in OotP?

For example, are we given an ample description of Tonks as a women 
or just because her Metamorphmagus abilities (does someone speak of 
the sex of Metamorphmagus?)

I would like to hear what you think about it.

Laurence

P.S. By the way, I'll introduced myself: 24-y-belgian girl, first 
language French (English 3rd, it explains bad grammar), electrical 
engineer, part of "Women in Sciences"(WiSe...), HP fan, HG/SS 
shipper.