I have been working on art requests for awhile that I realize that I don't have enough of my own content in my gallery, so here's the reason of why I wish to work on that..
Having a gallery full of requests you've done can help demonstrate your range and abilities, and taking requests are great for expanding your skill set. But making your own content expresses your personality and interests, these are important (if not more) because they can show where you intend to take your talents. Personal content could relate toward your interests for storytelling comics, designing creatures that could be used in video games, or perhaps to enter certain NSFW territory. Your personal content has ways that could connect you to relationships, project participation, or specific job opportunities you may seek. Having a balance of both requests and personal art can help you in that aspect.
With a gallery, it shows what topics you're familiar with as well as topics you may be willing to explore. Having plenty of references people can look at also makes it easier for people to make a request; people would have an idea on what sort of art you create, and it can help them determine what is acceptable and what is not. Of course, there are those requests that may try to work around your rules, to which may either be "This is new, but I think I could enjoy this", or "This is overstepping the boundaries for me".