Wesker’s organization mainly came to steal the Plaga virus/parasite
just as umbrella did with in africa where they stole the Progenitor plant to create their virus
and sure Krauser’s character wasnt expanded upon until Darkside Chronicles, but RE4 had more horror into it than RE5 (i love feeling horrified being alone in a room with the chainsaw guys or any other powerful enemy with fatal 1-hit kill attacks), and that feeling that you probally dont have enough ammo to kill the boss also made the player feel tense
and the merchant was gold