What factors led to the convention replacing the caucus as a widely used nominating method?

I believe the answer is: we want our voters to educate themselves without outside opinions conflicting with our own beliefs that affect our voting choices

In a caucus, the representatives of each party for the presidential election is appointed by the voters, not the party. This make a lot of them appoint only someone that they know directly (such as friends and relatives) . Due to the complication of this method, the process changed into convention, where the right to choose the representatives for presidential candidates belong to the party.

these acts divided the south into five military districts.