Haven't played since season 3. Question about draft pick.

When I last played, the ban phase consisted of two team captains, aka the first pick take turns to ban 3 champions, before it moves on to the rest of the team picking a champ to play.

Then it's changed to the last 3 picks doing the bans.

And now every player can pick and choose their own champ to ban.

I can understand the most recent change, but I want to know, why was the original ban phase changed? What was Riot's thought process behind the decision to go from first pick to ban to last 3 players can ban? When was this change and why?