It could be something to do with how society views that. Guys are expected to be the brave one, the one who takes the initiative, the one who goes after the girl. Whereas if a girl does that, it is frowned upon by many. Even though our society is starting to become more open, there is still a part of us that frowns upon aggressive females, whether we do it on purpose or not. Being the girl who texts first kind of makes her seem like an aggressive person (even though that it is totally not true) and I suppose some people have a problem with appearing that way.
Other times it could be that these girls have a strange notion in their mind that if the guy texts first, it'll be romantic or whatever. Most guys don't text a lot or aren't into verbal communication beyond talking, so when they do initiate a text (or any sort of verbal communication that isn't simply talking), it's like "wow, they actually like me". Girls want to feel this way so I guess I can understand their reasons for wanting the guy to text first.
And you can't say all girls want this. With me, often times I'm the one who initiated the text because if I just sit around and wait for guys to text me, I'm not going to get very much done. Although I must admit that I do like it when a guy texts me first, because it shows that they were at least thinking about me, whether it's romantically or just as a friend (although usually as a friend since no one has ever actually liked me before). It makes me feel good and appreciated and that's what counts.
