The first part not only isn't new, but it is actually in use by some companies, check Minecraft. In fact there are entire websites around this idea.
The second part sounds somewhat between impractical and infeasible.
First, you would need entire teams devoted to implement and test random suggestions just see "what sticks", hardly a good use of resources.
Second, and most importantly, games are a complex network of interconnected rules, and changing one thing can ripple through the entire design. If something seems to work, is because of that single change in isolation, or is any permutation of the 20 different things that you are testing at the same time?
Though most everything is just "under consideration" on featureupvote.com it would be nice to have a true road map for things that are actually coming. Game changers and not just swimming pools.
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Just so they can have a platform to let their community know they are listening. Most SaaS companies have a version of it... Additionally, it would give US the ability to see what others are saying and we could vote if we agree or disagree. To be frank, I disagree with some people's feature request because it detracts away from the value of the product.