Given identical money payoffs between two options (even when adjusting for non-linear utility of money), choosing the non-ambiguous has the added advantage of giving a limited rationality agent less possible futures to spend computing resources on while the process of generating utility runs.

Consider two options: a) You wait one year and get 1 million dollars. b) You wait one year and get 3 million dollars with 0.5 probability (decided after this year).

If you take option b), depending on the size of your "utils", all planning for after the year must essentially be done twice, once for the case with 3 million dollars available and once for the case without.