Because you can deduplicate certain parts of the logic which make the whole thing less error prone, such as

    if c
      x=1
    else
      x=2

If I ever want to change x, or refactor this code some other way, its a more brittle process over x=c?1:2

The ternary expression also takes up much less space so there is less of an emphasis on it, this can be a stylistic tool in a programmer's toolbox