In the new system, your chance of winning is the chance you roll high enough divided by the number of useful items that boss drops for your class. Now, they could set “chance_of_rolling_high_enough” to an arbitrary value, like 10%. That’s what I did in my example. Then you’re truly independent of other players, because you could all win one item, or nobody could, or anything in-between.
It's true that individual rolls don't affect your chance to get loot. Blizzard can already juke various constants to change the rate you get loot, and that will be no different in Pandaria.
What individual rolls give us is a much improved social dynamic around loot awarding. Ever see people in LFD complaining about each other's sack of helpful goods? No? It's a much less dramatic system, isn't it!
One of the ways individual rolls improve things is that it removes raid makeup as a factor in whether you get loot. You can't improve your chances by kicking people who use the same gear as you, and you can't improve your chances by stacking a raid with friendly guildies. If you've played any in LFR (and who hasn't?), both of these kinds of behavior are rather annoying. It's not the way it is supposed to work.
Assuming Blizzard also removes the ability to trade looted items, thus making it a truly individual award, players won't be hounded by after-roll swap negations. When these happen in a guild run, I find it draws us closer together. Both participants will give an honest assessment of how much they need the item, and if one gives the item to the other, they have some expectation that the loot karma will come back around later. In an LFR run, it's almost always fun-sapping. I don't enjoy comparing gear with someone to decide if they really do need something massively more than I do. Also, nobody who asks to buy an item ever asks a reasonable price; I think a thousand gold is the bare minimum for raid gear that you buy instead of win, but people seem to expect to buy items from me from more like a few hundred. I only recall once having a good experience with tradable loot in LFR; otherwise it's been a drag.
I welcome the new individual rolls for LFR. I prefer raiding with a guild, and I really like my guild's loot system, and I like after-raid trading when in a guild run. When I'm in LFR, though, there's no social context outside the raid. We're all strangers when we start, and we'll all be strangers again afterwards. It's fun downing a boss with strangers; that much has worked well. It's not fun sharing loot rewards with them, and I'm glad that part of the system is being redone.