That's fair, a lot of these features do not require a beefy processor. I think the value lies in the AW being a full-featured platform. Its processor is overkill for the lightest use-cases like remote shutter, but for others it's nice having a smartphone-like experience.
Case in point: Maps are full featured, it's not just about traffic, it's also about points of interest, supporting different modalities (crucially, public transit), and generally feeling like the full maps experience.
Like any other platform, 3rd party apps are nice for niches that the manufacturers do not serve, or do not serve well. For example, lifting apps make it super easy to log sets, reps, rest, etc; useful data the core experience does not offer.
As mentioned earlier, I think there's room for both. I'm actually not opposed to sporting a Garmin for endurance sports, where battery life is king :)