There is a difference between what "can we do" and "know how to do". There are a lot of things that haven't been done in bully modding yet but it's not because we don't know how to do them, but rather because it's out of our reach. For example something that has been wanted for a lot of time was to decompile and edit .cat files, the files that contains the fighting moves from each fighting style. Until this day nobody released an edited .cat file that was decompiled, edited and then compiled back...and I'm not talking about editing the file while it's compiled. Another thing that hasn't been done is to make a major modification to the map, like mapping in gta san andreas (not talking about simple prop spawning but like spawning a whole new place like an island idk). This is because bully modding is not as popular as gta modding...so there weren't many modding tools released.
Short answer: Like chuck said, you can create insteresting story mods or something else. Because there are a lot of things that we can't deal with yet doesn't mean that you can't start with the simple stuff that we have discovered for now.