Alex,
Einstein thought that equations and relationships that were messy, complex and ugly looking were probably wrong - he preferred simplicity and beauty in natural forms and processes (probably explains his long opposition to the fundamentals of QM - not sure if he changed his stance by the time he retired).
(I recall a German Physicist named Peter Bergmann who visited our University in the early 1990s. He gave several public lectures on the various Unified Field Theories that were floating around at the time. Many of the questions that were fired at him after his talks related to his relationship with Einstein. He told the audience that Einstein never stopped working on these ideas - it must be a tough nut to crack
)