The goal was to get improvement over scrypt. Scrypt is good but it can be improved. For example robustness against side-channel attacks.  There are also some seemingly minor issues like the need to keep password in memory until hashing is done, complexity of the scheme,   parameter selection and user-friendliness that can be important if the algorithm is widely adopted.<p>btw. Colin Percival (creator of scrypt) was part of the committee.