2D is design in such a manner to haev personality trails that are "perfect" or to be very attractive and cute. 3D has a lot of flaws, while 2D flaws has "none", and those who exist - can be turned around to something good and attractive, as example as Tsundere or Yandare.

If you look at Love Live, there 9 girls - and they are all design and created for you - as teh viewer - to at least be attractive to one or more, as they all very cute but in their own way!