The main practical benefit of object wrapping (ActiveRecord in particular) is that it gives you a more structured way to lay out the model-related logic for your app. Callbacks, model validations, and associations in particular allow you to easily compartmentalize a lot of the details of your models. If you're looking for ways to reduce the complexity of the problem space in your head, ActiveRecord et al are great ways to do it.

(ymmv. If you eat, sleep, think, dream, and make love in SQL, I guess you might as well ditch the ORM)