This is based on simple observation and not quantitative analysis...
But the big difference between Maroney & Morris is their deviations from their average. Morris is just more consistent than Maroney is; and most fans; as well as coaches prefer consistency.
Lets say Morris 80% of the time gets between 3 and 5 years. Lets say Maroney gets between 3 and 5 yards 40% of the time; and 50% he gets under 3 yards; and 10% he breaks one huge.
When its 1st and 10, you might prefer Maroney in the hopes of the big play, and if it fails, you still have 2 more chances.
When its 2nd or 3rd and 2 though, Morris is a better option cause you can almost bank on him getting it; whereas you can't with Maroney and you're just as likely to lose yards as you are of getting that 1st.
And thats why people love Faulk -- who would be #4 on the depth chart when everyone is healthy; Cause when its 3rd and 8, he can consistently be counted on to catch the short pass and get the first.
If Morris/Jordan and Maroney are healthy then its all good cause you have both 1st down and 2nd/3rd down options. But if you could only pick one, I'd pick the consistent one.