I am with Vrem and Tad on this one - the number of possible combos we already have should keep anyone happy for at least one life time
As a KittyCatS Auctioneer... I know adding more traits and permutations will make it even more complicated to go through the pedigrees and do them any kind of justice!
As a RL Artist - I think that cats are born with basic eye shapes - the rest of the things being mentioned are a cat's expressions.
To have an expression as a permanent look... hmmmm..... be same as a person walking around looking perpetually surprised! LOL
What would be nice perhaps is to have a greater range of expressions rather than more traits.... just my view!