Had it never occurred to you that AVB might always have intended to make Hugo his no. 1 but that he understood that Hugo had:
a) never played in the Premier League before - hugely significant, given how different the game is in England, as any goalkeeper who has moved here from abroad will tell you
b) joined the club two weeks into the season, with no pre season during which to get to know his team mates or to become familiar with the team's pattern of play
....and that, consequently, he wanted to ease Hugo gently into the first team rather than throwing him in at the deep end and exposing him to the risk of making rookie (in England) mistakes which could have led to the players, the fans and even Lloris himself losing confidence in his abilities? Certainly, with a keeper as solid as Brad as an alternative, there was no need to take that risk.
Had it also never occurred to you that when AVB summarily dropped a couple of popular, senior players at Chelsea last season, it triggered dressing room unrest (if not outright player revolt) that led to their patchy form and his ultimate dismissal? Learning from past mistakes, rather than mindlessly repeating them, is a good thing.
You ask why there is a heated debate. The answer is because there are some people who are determined to find fault, even where it doesn't exist. Some found fault with AVB for not putting Lloris in the first team straight away. Some found fault with AVB for dropping Brad. The bloke can't win. It's pathetic. We're supposed to be on the same side (not that you'd know it) and, rather than bitching endlessly, we should all rejoice in the fact that we have a brilliant keeper like Hugo in the first team and the best possible no. 2 that any club could hope to have.