From the opening of Universal Studios until January of 2002, the street actor department was called Celebrities. It is now called USF Atmosphere. One reason they eliminated the Celebrities is the same reason they scaled back on everything after 9/11: Money. Each of those intellectual properties we call a Celebrity cost Universal 10K per year to license. After 9/11, only 5K guests were coming through the gate every day as compared to 25K-30K. Universal looked to cut back anywhere they could. Think about it: 30K for Marx Bros., 20K for Laurel and Hardy, 20K for Ricky and Lucy Ricardo, 20K for Mae West and W.C. Fields, 10K for Marilyn Monroe, 10K for Charlie Chaplin...etc. The only Celebs that survived the cut of 2002 were Ricky and Lucy Ricardo. This was most likely because Universal was afraid they would lose the rights to the Lucy Tribute if they cut the appearances of the characters.
Another reason Universal cut the Celebrities was casting. Many professional lookalikes are accustomed to being paid up to $150 per hour. Universal paid $15-$20 on average per hour. This played into other issues that caused a lot of union/Equity talk while the Celebrities department existed. Quite possibly another reason the department went through a big transition.
Marilyn Monroe has made a return and now joins Ricky and Lucy Ricardo during daily operations. An interesting part of the process for Lucy and Ricky Ricardo is approval from the Arnaz estate. After Universal has their auditions and fittings and trainings and cuts for the Ricardos, FINAL approval for each actor has to come from Lucie Arnaz. Any Ricky or Lucy has to be video recorded and the clips are sent to Ms. Arnaz for a “Yes” or “No”.