I don't have tons of experience but it sure does seem to me that the equipment does need to fit the situation. My bike from 1996 to 2010 was a Trek 520... I think it had 28mm tires. Hauling down hills and hitting potholes at speed... I do believe that's how my rims got a bit funny. At that was without luggage! So on my new bike I have 50mm tires! Plus a Brooks Flyer = a sprung saddle.

There are lots of reports of broken racks around. Actually wider tires at lower pressure ought to cut down on shocks to the racks, too! The challenge of course is that wide tires needs wide enough rims and frame space.

Wider tires are nice but probably thicker tires won't help much. If you're on gravel or something then tread is nice but if the surface is solid then smooth tires should work. Thicker tires can help with flats too but that's more a matter of debris that roughness.