Originally Posted by T-Mar

Arabesque is only a nickname used within the cycling community to facilitate identification of the group. While Shimano did use the term arabesque to describe the ornamental design, it was never part of the offical group designation. The same applies to"GoldenArrow",which is the nickname for 1st generation Shimano 105.

While I don't know the actual reason for not stamping components with "600EX" or "New 600EX", I believe it was a case of not wanting to confuse the consumer with too much information. "600" was sufficient to indicate the relative level of the group within the Shimano hierarchy and new generations of a group were typically self evident via styling changes and/or new features.