I'm too lazy to remove the cello from every cigar before I introduce it to the humidor.

Seriously, cellophane is somewhat gas- and water-vapor permeable. It may slow aging a bit, but patience is a virtue; either leave it on or take it off, your choice.

Cello also provides a degree of protection for a cigar. Some people remove and save the cello, then put it back on before filling a cigar case or ziplock bag. That takes even more effort than just removing it and throwing it away, but it probably does slow moisture loss a bit while traveling in a case.

I do remove, or at least open, the cello wrapping around entire bundles, and remove the plastic or cello wrapping on boxes before I put them away to rest. One layer of cello I can accept, but two or more would interfere with aging more than I want.

Of course, I also remove the bands before I light a cigar, most of the time. A pretty band tells everyone what you're smoking, but I don't care if people approve of what I smoke. Besides, it's going to have to come off anyway once I've burned the stick to the bottom of the band, and want to enjoy a few more puffs before tossing it; might as well remove it before I light up, assuming the band is not adhering to the wrapper.