Another example is Solovays result to partition any stationary subset $S \subset \kappa$ into $\kappa$ many staionary subsets of $S$. It is mentioned in Jechs book that Solovay first used a generic ultrapower construction to prove this. Later a more elementary proof was found, using no 'metamathematical' concepts as forcing or ultrapowers of the universe, similar to the history of the proofs of Silvers theorem.