The problem with simplifying the posting process is removing options that people can select to personalise the experience and make themselves found easier. 

Some things could make it easier though, like having a box to quick search a fandom, and if the fandom isn't there, it can make a new gallery. That can come up with types though. Also making mediums an option people can chose (default to not stated). Also remembering common gallery options could speed the process up. Deviantart does this and I'm very thankful for it considering the hundreds of galleries they have now. Having it all inline may also make it less intimidating. IDK. I don't have an issue with the submissions but if I was nitty picky, I could suggest that...