This is a very important feature even with the low demand as @christian.krammer states it. You shouldn’t ignore the fact that there are tools that we may not use regularly but when we need to, they are no alternatives or workarounds. In this case, not even mentioning the digital era we live in, do you actually think adding links to artworks is not important and/or necessary?
As you develop features based on demand, also look at the features that may not be in demand by masses but are vital to the design process and/or outputs. We want to be able to use Gravit on its own without having to rely on other design software for simple things like adding a URL. Because then what’s the sense of working halfway and transferring work to another software to complete?