As a designer/illustrator, it's important to have a nice library of textures and other assets that you can pull from while designing. A lot of times I end up creating textures and other assets specifically for the project, but when it comes to needing some basic color textures to add to backgrounds or inside of text, I often times pull from my library of pre-made textures. This makes designing easier and quicker. There are lots of ways to create your own textures and I put a lot of importance on creating my own assets, but background textures can be used in so many ways for so many projects. That is why my Creative Market shop features quite the plethora of texture options that are completely ready to jump into any any project. Of course, all of this is assuming the type of design project that you are working on is one that utilizes textures. If you are all for super clean solid vector shapes only, then textures might be the devil to you. To me, textures are like biting into a nice juicy hamburger with all the fixings.
I have 2 large texture backgrounds that would work great for building out your textures library. You can find these backgrounds at my Creative Market shop or from the links below. https://creativemarket.com/jheglund