Nintendo sees it as cheating, but generally among cloners the idea is that events are pretty much no choice; it's not expected that North America is going to get its own Surfing Pikachu, for instance, so if we wanted one on August 9 - when it was released - the only option was to give over a much-demanded event (people were demanding foreign Charizard or WC Aegislash events, for instance) in order to get one, and even then that one received is a clone. I finally succeeded in getting a clone late in the day from someone who had seen me wandering about during the day and who seemingly realized I didn't have any of the demanded events that people refused to let go a simple CLONE of the Pikachu for.
So, for instance, I could even offer a clone of a Minato Mirai Pikachu instead of a Shiny if you want; it's actually more valuable than a Shiny. :) I hope to hatch all of my own Shinies someday, but for now I'm simply Dexing them, and the reason I want to clone them is because I can then offer them as trades to help my own Shiny collection while still allowing you to trade them. You can even ask me for extra of them over time if you'd like. :)
So yeah...cloning is cheating in a way, but the way this one works is through backing up save data, something that can be done anyway with the device in question (and someone came up with the cloning idea from that), and not by, say, holding down the Select button while moving Pokémon (which is how cloning is done in Generation V). There is no cheating in this method, but it's more of an exploit provided by the existing hardware. Bank has no idea you restored the save data. You can move your entire PC into there and restore the data to get a copy of everything. Most people have no need to do that, however, and the majority of my cloning is events, 6IVs, legendaries, and Shinies. I haven't cloned every 6IV, either, as once you have one breeding another is a piece of cake with the Destiny Knot. That said, my Gym team DOES feature some 6IVs. :)
Also, my basis for why cloning Events is legitimate? Think of an Event distribution this way: it's a Pokémon generated by a system that Gamefreak/Nintendo creates, and it generates unlimited copies of the event. The key word here is "copies". If you look at it from that angle, an AR device only does the exact same thing, but changes it so you can get as many as you want. The 6th gen. however only hacks in Wonder Cards, so that's why you'll see a list of hacked Wonder Card dates in the trading forum that people try to avoid. For shorter events, this is harder to do. I might one day hack in a Mega Kick Pikachu since it's going to have the same date as any traded one, anyway; I just wouldn't offer it for trade without noting I got it through a device. It should be noted that, as yet, I have not hacked a single Wonder Card.