So your argument is that because bonus rolls is RNG, therefor the system we have now (which involves more RNG) is better?
Bonus rolls would allow players to target specific items at a greater rate than what is possible right now. For example if you really needed a better weapon, you could bonus roll on Denathrius and/or the other boss that drop a weapon token for your class.
The weekly vault is not the same simply because it doesn't allow targeting at all. Personally I have around 30 items avaiable in CN. This means that the weekly vault gives me an additional chance of getting 10% of those items to choose 1 item from.
Also, 25 man raids did NOT drop 4 items back in Cataclysm. I was sure it was 5 items per raid but I went and looked at old kill videos and it seems to be 6 items PLUS tokens in 25 man raids.
But again, I'll repeat what I said in the first post.
Many people seems to have an idea that less loot => people will be running CN for longer time => content will last longer.
My prediction (and fear, because CN is actually a good raid) is that this won't be the case and that players will simply get frustrated with the rewards in the raid being to minimal and insignificant it will put them off of raiding (and possible the game) in general.