An "Easy" task fails 7 out of 10 times?

[Geron Raveneye]

Recently I did some number crunching on probabilities, and the effect of bonuses on the outcome of a check with a certain CL, and I've got to say it made me go quite a bit. Namely, with the current set of challenge bases 12/18 C&C is employing, and a 0-5 CL for "Easy" tasks, a 1st level character who has a +1 bonus in his Primary ability will fail 50-70% of the time upon making a check.

Does anybody else think that's a bit often for something labeled as "Easy"?
I know C&C emphasizes narrative problem-solving over dice rolling, and advises dice be only rolled when the outcome is important to the story at hand. Still, IF have characters roll for something and label it "Easy", should the failure chance be that high already, even if it's low-level characters? I can only wonder if that's not too discouraging for players who start at 1st level, making them groan every time the CL makes them roll for something. Is this so dice rolls won't come up much, or because the characters are supposed to be pretty incompetent at first so they can enjoy their competence at higher levels? Somehow it simply looks pretty discouraging to me, since there will be challenges with worse than "Easy" CL in most adventures as well.

To compare, I view something "Easy" as something an average character at low levels can succeed at 80-85% of the time, which for C&C would translate as a total Challenge of 6 or 7 for a Prime attribute.