Why the sudden change?
After a backlash from fans about the design of Sonic as to why he was given small eyes, human teeth and disproportionate legs, the character of Sonic changed dramatically in recent trailers. The original creator of Sonic had said he himself was worried about the design of the Sonic character in May.
Here is a before and after of the Sonic in May and the Sonic now.
This is the Sonic created in May time when an outburst of negativity from fans erupted, Sonic was said to be 'too human-like'.
This is the Sonic after being redesigned, many fans are much happier with this change as it fits the characters' actual appearance.
After the previous outburst of negativity from the first Sonic design, the film designer of the Sonic, Jeff Fowler announced he was willing to re-design the character of Sonic after the responses from May. Now here we are six months later with the redesigned Sonic that satisfies many more than it did before. Fowler tweeted "Today is the DAY" after announcing the new look of Sonic and he could not be more enthusiastic to show everybody this new version of sonic!