But Noctis only got one redesign around 2010?
OK, gonna make a post simply because I wanna see if what I'm saying makes sense to me.
Noctis, Gladio, Prompto, Ignis changed from 2006 -> 2008 (which were admittedly prototype designs) after Nomura inked his name in blood to get the lifetime's supply of Roen attire.
Noctis also changed slightly from the AC Complete trailer design to what we have now.
(AC Complete trailer design)
(current design, probably from 2011 onwards)
Stella changed from the 2008 DK Sigma trailer to the AC Complete trailer design. She was changed again to what we saw in 2011. That wasn't enough though, Nomura changed her again to Leanne from RoF in 2013.
(DK Sigma trailer, this was probably a prototype)
(As an aside, it's funny how we always point to Stella being some ruthless badass antagonist to Noctis, but she's all teary-eyed here when she battles him. We didn't know anything about her character to make any assertion about her character.)
(AC Complete trailer, couldn't find one just with Stella)
(same design, but I wanted to show this since it was my favourite version of Stella/Luna and it was captured very well in-game)
(Stella from 2011...)
(Leanne from 2013 and not Leanne 2015)
There's more I can post (Prompto and Regis), but the point I'm trying to make is that Versus XIII had its fair share of character design changes from 2006 to 2013. What we have now is still very faithful to what we had before regarding character designs, other than Regis who has a different face now.