Please keep the System as it is, it's good.
First things first, loot should be random getting items excluded takes the random chance away. While sometimes it might be frustrating that you don't get an item without RNG you would end up with all you items in two weeks and one of the major factors which keep the content interesting after you cleared it several times would disappear. Short RNG is part of the game and should stay part of the game, even if you may deny it, it is clearly shown that items are one of the main long term motivations of games.
Secondly, why can't you give other players the bonus items? Well YOU did the extra work to get the coins so you should get the bonus and not someone else. While I might like to give my items to other players in case I don't need it. It's just the principle of the bonus loot system a person putting in the little extra effort should get a bonus, a person who doesn't shouldn't.
And don't forget that when you raid normal or hc, you still can share the drops. While I agree that it sucks that you can't trade the LFR dropped items (and only the non-bonus dropped items!). The new loot system there is the consequence of all the greedy guys who needed stuff for other people or who simply didn't need them. And while (like I already said) would like to share the drops, I still prefer the new LFR loot system 100% more than the old when, because I can accept not getting items or double items, but I can't stand people who roll on items they don't need or just for a friend.
Finally there is (at least I assume there is) also logical reason behind the non share policy. First of all in LFR, if you could share items, they had to reduce the dropchance because otherwise, you would get items FAR faster than before. Everyone has +- the old chance for an item add it up with alle the players who share loot table with you and you receive far more loot. Thus comparing with the old system there had to be only around 4 players in the entire raid which get items. This would be horribly frustrating, especially if people weren't so nice to share their loot with you.
As for the bonus roll, it's already a great advantage if you compare it to the old system.
Let's assume you raid 10man with a 12 bosses tier. Say every boss drops as usual 2 items, so you would recieve 24 items.
Now lets see the new system, lets assume everyone in the raids did dailies and has 3 coins (as it is usually). Now you have 24 items + bonus rolls. Let's just assume it's the same chance to win a bonus roll, than a lfr roll. And since in lfr the chances nearly didn't change we should have a 4/25 chance (4 Items for 25 people). I realise this isn't correct but lets just assume it. Then you would get 10(players)*3(coins)*4/25(chance) = 4.8 bonus items. Let's round it up to 5 and you would get 29 items instead of 24. Which would be 20% more items than before which is huge.
And this just average you also might get up to 30 bonus items (which is of course nearly impossible, but possible)
So as you can see it would dramatically increase the loot, which would have:
a) a reduced drop chance in raids as result or
b) a very very low dropchance for bonus roll loot.
Finally I would like to say the only change, which I is the addition of vanity and other bonus items in the bonus roll, which they have been talking about. Something like in the satchel you get from Dungeon Call to arms. (For those who don't know: chance for gems/pots/flask and very low chances for pets&mounts)