Simulating the relevant hardware. For example this year we added Nearby Interaction support to Simulator, something macOS doesn't support. In addition Simulator supports watchOS and tvOS devices.
Simulating the relevant device experience. Running iOS apps directly on macOS will have a Catalyst-like experience which is not the same as running an app on an iPhone or iPad.
Run this years iOS/watchOS/tvOS on last year's macOS which wouldn't be possible without the simulator.
Run multiple Simulators concurrently.
An environment isolated from your personal setup inside macOS (eg accidentally deleting all contacts or importing 10,000 copies of a photo doesn't pollute your personal contacts db or photo library)
Since the new Mac running Apple Silicon and MacOS 11 will run native iOS & iOSPad apps, has this changed the use of the Simulator when creating iOS apps with Xcode? Will the Simulator been needed, or will it disappear? How will source level debugging (with break points and Instruments) change with the new hardware? I am sure that you can still debug on a tethered iPhone the same way, but the majority of our programming and debugging is done on the Simulator. Thanks!
The simulator provides several things that are as important as ever: