You can come up with a thousand excuses to explain the absence of women on screen (e.g. they were all killed by the Klingons, wiped out by space herpes, busy making the tea etc) but they are just excuses. The writers and casting people are sexist for not employing actresses and stuntwomen to play Romulans. It gives the appearance that the Romulans are sexist to say the least.
Whats your definition of sexism?
Edit: Nero, goes out of his way to destroy the Federation and possibly the Klingon Empire to save his wife and child, and you call him sexist?
I think we have to distinguish the sexism of the species from the sexism of the writers and casting people. The Federation is supposed to espouse equality and women make up roughly 50% of humans but we do not see 50% female security, female captains, female admirals, and the women that we do see seem far less likely to get any lines.
The Vulcan woman may indeed have been T'Pau. She was the only woman and she didn't get any lines, so she could be anybody and they didn't demonstrate Vulcan equality.
Conversely, if the Ferengi have no women on ship we can say that they are sexist but that the casting and writing is correct.
Further, there are several high profile recurring races that treat women less favourably than men but no recurring high profile races where women are in charge. On two occasions where women have been in charge the male characters have shown an aversion to that kind of political structure.
Star Trek as a rule scores quite poorly on subconscious sexism. Several high profile female characters that we've had (7 of 9 & Rachel Garrett) were originally written as male and were changed later on. A lot of other characters are written as male and remain so.
TOS starts off with an imbalance because so many of the main characters are male but, instead of redressing that balance with the suppporting cast, we see the opposite: most of the supporting cast is also male and two of the three main recurring female characters are largely absent.
Nero's motivations are not sexist in themselves, although they are a bit cliche. Go back over Trek history to see how many grieving husbands/fathers have been bent on some kind of revenge. Now see how many grieving wives/mothers have been intent on revenge. I suppose we can sort of count Lenore Karidian in TOS.
In spite of its sexist roots, TOS did put a bit of effort in to demonstrate more equality than the time in which it as made. Modern Trek cannot say the same. DS9 probably came the closest but even there you had quite a large imbalance between male and female characters.
Sexism for me involves not accepting a couple of high profile women as equality. Margaret Thatcher was a woman at the top but she had no other women in her cabinet so I would say that the sexual imbalance indicates sexism in her government.
So for me, Romulans are supposed to espouse equality and yet we do not see an equal number of men and women on ship. I'd let the Klingons get away with it but it is not acceptable for Romulans. And yes, we can all come up with hundreds of possible reasons but many of those will involve sexist notions based on current thinking but the fact remains that there were few women because they chose to cast few women. Sexist.
