The above is a long but interesting history of the Republican nomination process. Prior to 1972 the nominee was chosen by consensus by party leaders for each state. The Democrats had a similar thing, but the liberal democrats wanted the people more involved with primary voting and open caucuses and such. The Republicans followed suit.
The author of the piece (written in 2013 after the failed Romney election) argues that the way we do it now is a failed process with the long nomination process, all of the dirt being thrown that weakens the eventual nominee, the money involved (with less to spend on the national election) and the divided spirit of the GOP.
Agree. The current process is a mess, and has been for some time.