Gotta say, I prefer my Jabba referenced in conversation, building him up, until his reveal in ROTJ. It works perfectly and opens ROTJ on a note of suspense. The original plan WAS to have included him in that one tiny scene in ANH, but I think it would have ruined that beautiful sense of dread than one shares with Leia and Co. as Han is taken away by Boba to face his fate at the hands of his nemesis Jabba the Hutt..........and that same feeling of foreboding as everyone heads for Jabba's palace at the beginning of ROTJ to rescue him.