From Wikipedia (http://en.wikipedia.org/wiki/Regular_expression), "In computing, a regular expression provides a concise and flexible means to "match" (specify and recognize) strings of text, such as particular characters, words, or patterns of characters. ... A regular expression is written in a formal language that can be interpreted by a regular expression processor, which is a program that either serves as a parser generator or examines text and identifies parts that match the provided specification. ... Regular expressions are used by many text editors, utilities, and programming languages to search and manipulate text based on patterns."
By enabling the use of regular expressions everywhere that the need exists to search and/or manipulate text based on patterns (for things like searches, attribute string format constraints, etc.), PTC would be supporting an industry standard which is much more powerful, concise and felexible than PTC's current home grown (and often varying) methods.