Bullet journalling is an analogue task/time management system that can really be whatever you want it to be! It gives you the freedom to create a system that tracks the things you care about and helps you get things done in a way that works for you.
Beautiful artistic spreads are not the original intention of a bullet journal, however many people enjoy using it as a creative outlet. Because the system is meant to be whatever you want it to be, if you want it to be super creative then go for it! But if you don’t, you shouldn’t feel pressured to have it be anything more than a useful notebook for YOU.
Don’t overcomplicate your bullet journal or else you’ll find yourself getting overwhelmed and not using it. Start small, and add spreads as you go and think of new ways it could be useful for you.
The bullet journal can help you get a better idea of project scope as you move tasks you didn’t complete to the next day by hand. It has taught us to better estimate how many tasks we can fit into a day.