I do agree that every event should have a winner before ending it. However with a couple exceptions. Events like the jefferson motel stuff should IMO definitly have a winner, however parkour events (which will have to be possible ofcourse) don't need to have a winner as long as you don't stop it just before someone gets to the end or something like that.
Because SA really didn't have any GUIs whatsoever. And the GTA V style is simple, easy to recreate and clean and professional looking (IMO).
Furthermore we couldn't use default MTA UIs since all of our user interfaces are web based.