There is SOME personality in the character animation...like the Koopas that dance to the music. However, I do agree...that it is lacking.
The problem isn't really the character design, it is not putting the creative flare to the animation that give life to the characters. For example in Super Mario 64 I would say the art direction is not very inspired. It looks good, but honestly, I would not say Wow...Nintendo created characters and worlds that are magical. However, the animation flares made up for that. When Mario did his long jump, you felt like you were Mario straining to jump that far. He flung his whole body forward and it just felt right.
There were many moves and actions that felt that way. I also really loved the swimming in Mario 64...as another example. However, everything in New Super Mario's animation seems less than inspired.
If you are going to use 3D models that are easier to animate please play with them more. I want to see Mario's triple jump and his third jump he rolls into a ball ala Super Mario 3 star...and give him invincibility during the jump...to kill enemies over him...or just give him some flare in his jumps.
Personally I always wanted a 2D Mario that had all the moves of the 3D Mario game...minus the punching. Let him do back flips, long jumps, triple jumps, Wall Slides, Grab onto ledges and pull himself up...swim in underwater sections to secrets, but have to worry about air. These things could literally change the entire level design of a Mario game.
And yes, I know the New Super Mario Series has given me SOME of that...and in those areas I really praise New Super Mario, especially New Super Mario Wii...but I still want more.