I can't seem to find an option to reuse a dataset across projects. Is there no such option? If no, is there a reason to tie a dataset to a project? I can't see a good reason why this would be the case, but many reasons why to create datasets globally/in settings (same as connections)
You can share a dataset from one project with another project by going to a project's settings and selecting to expose the dataset you want to use elsewhere. Furthermore, you can decide how to deal with project boundaries when building workflows in the global settings.