I guess it depends.
For one thing, cello helps protect against changes in humidity, it also obviously helps protect the wrapper.
For long term aging, i can see removing it, but don't you love to see the lovely yellow cello just as much as i?
For now, i'm sending more out than i'm smoking, so i leave the cello on...
for the first two reasons i stated above. Mailing in December/January is not the kindest conditions to subject a cigar to. Plus i can be a little less carefull about rummaging thru the humidor, when the sticks are somewhat protected.