Countless amounts of times I have tried to use hoppers and they won't work all that will happen is the item will bob up and down above the hopper for ages. I don't know what's happening but I think it should be fixed because they are a very useful item that just won't work.
I'm also pretty sure that all the AFK farms, redstone machines and such that will be built if hoppers work again will make the Server laggy as never before.
Yeah I know, also the fact someone could steal out of someones chest. I was only saying this could also be an issue. I don't want to see hoppers reintroduced to see the Server lagging badly, one week later, when everyone upgraded farms and machines. It is laggy enough by now IMHO.
There have been countless amounts of threads just like this asking for hoppers to come back. If they are implemented again, great. If not, then we will just have to live without them like we have before and now.
As people have said, Hoppers are disabled for many reasons. There is a logical factor in disabling them, but I guess I'd go Neutral on this.