Since that movie did well and spawned 2 sequels, the real conclusion is that the viewers didn't really care.
As for "the internet", there will always some small part of it which will obsess and/or laught over anything, doesn't mean they represent anything significant - not even when they're vocal.
Viewers did care: the teeth got changed before the movie was released. And, I don't know if you missed it, but it wasn't just one niche of the internet commenting on his teeth. The "outrage" went mainstream; even dentists were making hit-pieces on Sonic's teeth. I'm not gonna lie, it was amazing marketing for the movie, intentional or not.
