From looking at many posts on several different threads, the loaded dice make sense.
For instance someone not sure who, since I'm horrid with names, and it's been a couple days, okay I slept since then. Posted about how it makes people fell when they fail. It was a rather good post and wish I could quote it in it's entirety here. Yet not going through all the hassle, because I'm lazy.
One of the gripes is because of the percieved failure of the dice, that people want to pass, and get that warm gooey feeling, so loaded dice is to me a copout from Larian giving these people what they want. The quick easy reward that has spawned the threads that revolve around the anger over pass/fail. So I can see it, much like some, one of them freely admitting they use cheat mode. Right or wrong it's still in our hands to decide. From my perspective loaded dice is giving people what they want, a nearly 100% chance to get that win. Will I use the feature no, will others yes. either way if there is an option it's up to us to use it, and in the long wrong it's not going to hurt. Still it is as other threads speak of, with loaded dice just an illusion of choice, so there will be hate for it as well.
Normal dice is just that normal, so not much to discuss here I prefer them, because I prefer chance to play a hand in it all.
Flat checks is again to me another copout and probably an idea that came up for those that are stating in many threads that dice rolling is boring, or there are to many dice rolls, or the last example I can think of that it's not letting your characters skills/etc come into play. When by very nature of 5e and any dice based system it's a combination of dice (which is representing luck/chance/some others) plus your modifiers, and the other persons stubborness/resolve/views, beliefs opinions etc. Again not really damaging to those like me that want to use the normal dice, or even harming those that want to 'roll' loaded dice.
So Larian is trying to please these three types of people, and if it's simply a choice then there is no real harm in it, and it's a way to quiet, and appease those that don't want the traditional D&D experience.