The option to store presets and templates with a specific catalog is particularly useful when there is a need for the photographer to work on several different computers. For example, in an educational “lab” environment, a student might have all of their images and catalog on an external drive making it easy to move from one machine to another during each “open lab” session. If they choose Preferences > Presets > Location and check the “Store Presets with Catalog” option, any user-created preset (such as metadata templates, develop presets etc.) will be stored within the same folder as the associated catalog (instead of in the default location). The advantage is that whichever computer you launch your Lightroom catalog on, you will see your presets and only your presets (as opposed to all of the other students’ presets).
If, however, you are working on a single computer, I would suggest that you do NOT check the “Store Presets with Catalog” option. Instead, save your presets (and templates) to the default location so that your presets will be accessible if you decide to create multiple catalogs.