Atrial fibrillation is the disorder, Watchman is mitigating the risk of stroke caused by the disorder. Ablation should curb your AF, but the Watchman reduces the risk of stroke if your AF is intractable or if you don't want to treat it with any number of methods, including ablation.
No one should pressure you to do anything you don't wish to do. However, it must be said that an ablation really improves the lives of those who have a successful one. In some cases, coupled with the installation of a Watchman, you don't even need any further meds.