Hops have unique antimicrobial properties and they act as a preservative. In past history, when there was no refrigeration, steam pasteurization, or hermetically-sealed processes, hops were added to fermenting grains to inhibit the bad bacterias and fungi that would create deadly poisonous brews. Drinking beer was high risk activity- you might get drunk; you might get dead! Men who could successfully brew batch after batch of brew that didn't kill you were called "masters" and were very respected. You can bet they carefully guarded their brewing recipes! (Believe it or not, religious monks had some of the best recipes!)
Beer that tasted good didn't come into the picture until later. Brew masters took note that hop cones from some plants brewed a more palatable beer than others, and started selecting specific female hop plants for cultivation. This selection process was very regional; Germans selected their favorite plants, Englishmen picked theirs, etc and so on. Each region developed beers with flavors that have become classics - German Pilsners, English Stouts, Scottish Ales . . .
All this history has led to today. Cross-breeding and creating new Hop varieties is leading to a craft brewing explosion of new beers with totally new flavors and profiles. New combinations of hops and malted grains used with new brewing techniques create new brews daily.
I hope this has piqued your interest and get you to investigate further. There is some really cool info out there that should not be forgotten!