I think Utena was so wrapped up in her own mini-fame that she simply wasn't paying attention to anyone or anything else.  (Except Wakaba.)  She's a very introverted character in the TV series, despite appearances, to the point where even her choice of clothing is all about creating that shell of strength around her rather than having to actually interact and mix with the world around her.  She could keep her head down and muddle on through quietly (which is sort of how she is when she's in a regular girls' uniform, yeah?) or she can be that girl who wears a boys uniform and shows lotsa leg but she can't be one of the girls.

She has followers and fans, but Wakaba's basically her only friend.

And, for a complaint... I didn't like the manga-addition of an aunt for Utena (An Aunt for Utena, coming soon from CBC and Telefilm), because it detracts from the feeling of being utterly alone/abandoned that never explaining the intervening years gives.

Decrescent Daytripper wrote:

I think Utena was so wrapped up in her own mini-fame that she simply wasn't paying attention to anyone or anything else.  (Except Wakaba.)  She's a very introverted character in the TV series, despite appearances, to the point where even her choice of clothing is all about creating that shell of strength around her rather than having to actually interact and mix with the world around her.  She could keep her head down and muddle on through quietly (which is sort of how she is when she's in a regular girls' uniform, yeah?) or she can be that girl who wears a boys uniform and shows lotsa leg but she can't be one of the girls.

She has followers and fans, but Wakaba's basically her only friend.

And, for a complaint... I didn't like the manga-addition of an aunt for Utena (An Aunt for Utena, coming soon from CBC and Telefilm), because it detracts from the feeling of being utterly alone/abandoned that never explaining the intervening years gives.

You've put into words what I haven't been able to.  It seemed very natural that Utena would be like that, but not necessarily stupid.  In fact, almost all of her actions seem double sided.
I especially liked what you said about "That girl who wears the boys uniform and shows lots of leg" because I'm sure that's how she would realistically be seen.  Her gender could never escape her, and her fighting against it makes it more obvious, and therefor giving her an identity.  End of story.  No need to interact with other people as much, she's turned into a caricature, so people rarely question it.