I'm a total reteogrouch and loves me my classic rim brake bikes.

That said, here are a few factors in favor of disc brakes: Superlative modulation, all-weather capability without resorting to highly abrasive pads (e.g. Kool Stop salmon), zero rim wear, no aluminum oxide dust getting everywhere (ridiculously destructive substance), reduced rotational mass, superlative fault tolerance, auto-adjusting for wear (in the case of hydraulics), able to use very different wheelsets without having to fiddle with brake adjustments, easier initial setup, dead simple pad replacement without any fiddling with pad toe-in.