One redesign that got a lot of controversy is that of Merida, from Brave.
Her design, changed to be a part of the Disney Princess line up involves giving her a skinnier waist, a slightly older, more feminine face and extra detail and accessories to add in a 'princess' look. Even her pose is more feminine, and it's understandable to want to make characters fit in to a line up, yes, but this is not Merida's character. She is not feminine, she is not a traditional princess, she rebels against that and that it one of the main points of her film; there is no point redesigning a character if you are going to remove a lot of what makes them that character, which is why there was so much outrage at this redesign.
Another recent redesign is Dora the Explorer.
She has been quite obvious aged up, which is fine if it for an older age, but what part of her new design says 'explorer'? Nothing does. She has been made more feminine with a lot more jewellery, and made her look like something out of a Barbie or Bratz series of dolls. This is almost a completely different character, and does not seem to relate to the show at all.
Ben 10 on Cartoon Network also made redesigns of the characters to make it suitable for an older fanbase.
The characters are still recognisable, and their design makes sense - you could realistically see the characters growing up into these new ones, and they don't contrast the characters' personalities or make them seem completely different. This design is effective, to the point, and is pretty accurate for the characters. It also meant that the show could go in slightly darker directions, and evolve.
The Teen Titans redesigns are something that I feel very conflicted about. Teen Titans Go! is a reboot of the original, for a completely new audience. It makes sense that the designs would be new, leaving the darker more teenager ones behind to hit a younger audience that will consume a lot more merchandise, which seems to be Cartoon Network's main aim nowadays. However, I do feel like the designs work. They are accurate and reflect the characters well, while still keeping a very cute, smaller style that makes for some very fun animation. I think that the design of the characters (and even the backgrounds) are good for the audience and are effective designs, so I can't be all that bitter about the remake.
This could be interesting - a redesign with a purpose, rather than just for the sake of correcting sexism in design. For example, the character Starfire in the two images above (tanned, red/pink hair) is extremely sexualised in the comics, and the animation makes a great new version of her wherein that is not the case. All of the personalities of the characters are changed slightly for the comics, but it works for the animation (as does other superhero adaptations like Young Justice), so this could be a way of improving some designs. I would still like to keep personalities as close as possible, but obvious with some characters who may act more on the sexuality, this would not work for a younger audience, and I think that it would be fun to aim redesigns at a similar audience to Teen Titans.