Beyond that, you run into the problem of lobbyists. Not the evil type that is a stand-in for the word "corruption", but instead the legitimate "education" type lobbyists. You lose much of the institutional knowledge that prevents candy coated views of the world from taking hold. Honestly, how many of the randomly selected people are going to understand the trade-offs of each and every policy, be it economic, societal, political, industrial, trade, environmental, etc. Having experienced people who have been around a few cycles provides a base level of knowledge.