One major reason that pit traded options are much more commonly traded than their e-cousins in lots of underlying futures contracts has to do with the much more complex strategies in options. I am an option member of the CBOT, and in the pits, it is not uncommon to be asked for a bid or offer on a multi leg strategy like a condor, and then see that one order filled by two or three different people, each doing a different complex spread strategy themselves, with maybe one or two of the single legs filled from a simple, single leg customer order. In the pit, I can also execute complex hedges if necessary to offset the risk I take on by making markets like that, so I am willing to do much larger size in the pit, as I can immediatly hedge my risks somehow or another. There just isn't an electronic platform yet that can accomodate all that adequately.
Jessie