I guess my question would be: why would Cass of all people be sent to deal with someone like the Riddler in the first place? Given the somewhat incredible number of heroes operating in Gotham, what would the chances be that Cass and only Cass would have to deal with the Riddler and his clues?
Cass is a bruiser, and her skills are generally used to that effect. If Lady Shiva or some other super-fighter was threatening the city, you wouldn't usually send someone like Tim or Babs to deal with it, and if the Riddler or the Joker has some incredibly-complex death trap set up, you wouldn't send Cass.