Regarding the comfort aspect, I hesitated to note it because there are so many variables in bike design and execution that influence comfort, and I don't mean to imply that disc brakes themselves ruin frame comfort. And "comfort" is such a subjective topic anyway.
By "comfort", I mean only that the older bike frame designs that many of us have enjoyed over the years don't support disc brakes without strengthening of certain aspects of the frame. The thin bike frames of yore, that often delivered a very nice ride quality, often don't work well with disc brakes because of the forces involved. Forks and seat or chain stays must be reinforced or designed to be heavier/thicker/stronger/etc. Modern materials like carbon (as in the case of the ToughRoad's fork) help to mitigate this to some degree. Carbon can be designed to have a lot of strength in one axis and a lot of compliance in another axis. But it has drawbacks as well (it seems that cost and realized durability are two of the most prominent).
Larger volume tires can certainly mitigate the harshness of a stiffer frame, but the feel will still be different. And it's absolutely not that one is better or worse than the other. Most folks will tend to prefer the feel of either a modern aluminum bike or a more traditional steel bike. Both offer advantages and disadvantages. I prefer older steel bikes for ride quality and "feel" of the bike. I prefer hydraulic disc brakes for the smooth and consistent braking action, regardless of moisture level or mud/sand/grit. Historically, those two things that I prefer haven't been found in one bike (though that is changing). Steel bikes with disc brakes are often built pretty heavy (adventure riding, like Surly bikes). Hybrid bikes with discs (like many of us have on this board) typically have aluminum frames. My dream bike is my '97 Trek 750, but with disc brakes (as long as it rode the same). That'd be the ideal bike for me. Some modern bikes are close to that. I understand the Breezer Radar bike has a relatively compliant frame and ride quality to it. Perhaps the Jamis Coda does as well (but it uses narrower tires).
The great thing is there are so many options. The unfortunate thing is there are so many options -- where do you even begin?! I'm a huge fan of test-riding a bike before buying it, especially if you know yourself to be very particular about what you like and don't like.