In an article by Wired, Takashi Iizuka talks about the past and future of Sonic. The article itself is kind of a dry read but Takashi’s quotes are worth giving it a look. The quote below is about how Sonic team has wanted to make a 2D Sonic for awhile. What about Sonic Rush you say? Well I have no witty retort.
“We have had the desire to create a new 2D Sonic game for quite a long time,” says Iizuka. “However, it was difficult from a business perspective, because we [had] many 3D Sonic games released. We were able to overcome this obstacle with the emergence of online distribution. Sonic 4 kicked off because all of the consoles now have online distributions (XBLA, PSN, Wiiware) as well as handhelds such as iPhone.”