There was a party in Australia that wanted to elect MPs (or whatever equivalent) whose only job would be to delegate decisions to a panel of independent experts in each field (I think the panel would be elected as well, don't remember the details, but it would be something like doctors deciding what public health decisions should be, for example), and IIRC sometimes decisions would be made by having polls where every member of the party could vote if the policy was not related to some field in particular. I think that didn't get anywhere though, unfortunately, as the idea sounds pretty damn superior to having a bunch of know-nothing but charismatic people who decide on all sorts of things pushed by lobbyists whose interest not always reflect that of the general population (or very rarely do so).
The problem with that most important decisions cover multiple fields. For example public health decisions are not purely medical. They have financial and economic implications. They are sometimes tied to issues of personal liberty. They operative in a framework of laws. They are often organisational and management decisions (e.g. where to build a hospital, how many ambulances to buy).
In general important decisions require many different skills.
This will also lead to the problem raised earlier of experts making decisions that suit their own interests (and biases).
