Thank you sticky1202 that is exactly what I am trying to explain in my post.
I've understood exactly what you were trying to explain but, keep in mind that:
Our airports are designed for FSX, so we have animated jetways there.
On FS9, since there are not animated jetways by the program, we modeled as static, because most of user would prefer to use AES.
We used to have animated jetways in FS9 as well, way before anyone else. But this took a lot of work, because we also had airplane detection and different animations based on that. You can see an example of them at Cloud9 EHAM. But this was 4 years ago.
Today, since there's FSX, we have to do a different modeling for it, which doesn't apply to FS9, and lots of users asked to have AES support instead so, it doesn't make any sense to do a lot of additional work for FS9, that most user wouldn't use anyway, because they rather use AES.