The guys behind the Street Fighter Blog have posted their very first issue of The Street Fighter Magazine (.pdf).STM: ... Were T. Hawk and Dee Jay planned to be in SF4 along with Cammy and Fei Long, and in the end they just didn't make the cut for various reasons?
Ono: ... SFIV was developed for as many users as possible, and to remind gamers that a fighting game is fun. At the beginning of the dev. stage, I thought that fans would be happy to have as many characters as possible in SFIV, but when I went back to the origin of the SFIV concept, I realized that it’s not the appropriate way to make fans happy.
The main reason was because too many characters would cause a complicated rulebook for its game play. After balancing the characters between, from Alpha series and ST series, also diagrams, controls, popularity etc., we made a decision to not include T. Hawk and Dee Jay this time. This is the actual background of why those two characters from the ST series didn’t make the cut for SFIV.