The folks at Rivendell would tend to disagree with you regarding repairing steel vs. carbon:

Materials that fail fast are said to fail "catastrophically." Of all materials used in bikes, none fails more catastrophically than carbon fiber, and none fails more slowly than steel. You want your bike stuff to respond to trauma by bending and denting, not shattering and snapping. Metals tend to do that. And once that's covered, you want plenty of time and lots of warning between the onset of failure (a crack, for instance) and total material separation. Steel is the first place winner here, too. Reparability is desirable, too, and steel wins that one, also.

Another quality to consider in a frame material is how well it ages; the degree to which it stays strong as it gets old, and environmental stress in the form of ozone, ultraviolet radiation, salt air, and temperature extremes affect it.

In this regard, metals are far superior to rubber, plastic, and carbon fiber. The resins used to hold the layers of carbon fiber together degrade with exposure to ultraviolet.

I agree - based on personal experience - that steel frames are easily repaired. My (admittedly limited) exposure to carbon fiber frames is that they aren't so much easily repaired, but rather easily replaced.